Basic magnesium sulfate cement (BMSC) is a new type of magnesium-based cementitious material modified by the chemical additive such as citric acid or boric acid on the basis of magnesium oxychloride cement. BMSC has the abundant mineral resource for the raw material, low energy consumption of production, and high utilization rate of the solid waste. BMSC has the green and environmental advantages, such as the conservation of energy, material, land, and low-carbon emissions. The systematic research on the durability of BMSC is still needed if BMSC are applied to the special environment such as the ocean and saline soil area. The main progress of the durability of BMSC material in past ten years is summarized in this paper, which includes the water resistance, carbonization and resistance of seawater, salt brine, freeze-thaw of BMSC material. and the influencing factors, the evolution law of corrosion and mechanical properties of internal steel bars, the mechanical properties of BMSC components under the natural exposure condition for 869 days. The relative dynamic modulus of the elasticity and mass change, corrosion products, and the microstructural changes of BMSC in the harsh environment is studied. The analysis of mechanism is also conducted on the durability of BMSC. The durability performance of the BMSC material is related to the composition and microstructure of BMSC. It can be found that the stable and abundant formation of 5·1·7 phase, which is the main hydration product in BMSC, is the fundamental reason for the good durability and high mechanical properties of BMSC-based material. BMSC concrete is not prone to carbonation and the internal steel reinforcement is not easily corroded in the atmospheric environment. The main changes in the microstructure of the carbonized zone on the surface of BMSCs during the carbon dioxide curing are the transformation of some hydration product Mg (OH))₂ into MgCO₃. The long-term retention rate of the compressive strength of BMSC concrete is closely related to its initial strength before the immersion in the seawater. The polarization resistance R_p decreases with the prolonged exposure time in the environment of seawater immersion. BMSC concrete with the compressive strength of C40 or above, BMSC mixed with KLJ rust inhibitor or the steel bar coated with epoxy resin are recommended to be used in the environment of seawater immersion. The freeze-thaw life of BMSC concrete exceeds 40 times, far exceeding that of Portland cement concrete. Compared to PCC components, the BMSC beams and columns under the coupling effects of the acid rain and freeze-thaw have less degradation of mechanical performance, lower rate of the internal steel corrosion, and higher enhancement effect of cracking load. The effective additive, suitable activity of MgO, appropriate addition of polymers, 5·1·7 crystal seed, slag (or fly ash), and solution immersion of KH₂PO₄ or NH₄H₂PO₄ can optimize the composition of hydration product of BMSC, increase the stability of the 5·1·7 phase of hydration product, effectively improve the microstructure of BMSC, and enhance the durability of BMSC-based material in the harsh environment. The prospect for the application of BMSC material is discussed. Due to the advantages of BMSC, such as resistance to carbonization, salt brine corrosion, low transmission, and reinforcement protectio, it can be found that the BMSC material can be used in the area with harsh environment such as the ocean, western saline soil, and Qinghai Tibet Plateau after KLJ rust inhibitor being added. The military engineering, pavement repair of cement concrete, crack repair in the brick and stone masonry of ancient building and prefabricated construction have good application prospects in the harsh environments such as the Qinghai Tibet Plateau and saline soil area. Finally, the problems of durability are discussed as follows: the mechanism of microstructure formation and evolution of BMSC-based material under the harsh environment, the corrosion resistance of BMSC concrete to sulfate, magnesium, and chloride salt under the wet dry and freeze-thaw cycles, mechanism of corrosion resistance of 5·1·7 phase and BMSC concrete, the dynamic evolution and mechanism of intrinsic degradation of the interfacial bonding performance between BMSC repair material and the old material under the harsh service condition, the structural damage, disasters, and life extension and toughening under the interaction response of permafrost and engineering in the high-altitude environment, the stress damage, degradation of structural performance, identification of field effects and long-term performance, and design for the expected lifespan of BMSC in the harsh environment such as the ocean and saline soil, the mechanism of transport and failure of BMSC concrete in the harsh environments, the reinforcement and long-term protection system of the surface of BMSC concrete, the model of the rapid life prediction for BMSC-based material. This paper can provides the theoretical basis for the application, durability evaluation, and engineering design of BMSC in the harsh environment.