The flow field simulation and scanning electron microscope observation methods are used to analyze the surface micromorphology of a certain type of turbine blade before and after operation, and the effect of high temperature and high pressure environment on the surface morphology of the blade is investigated. First, in order to improve the calculation efficiency, according to the blade form, a periodic symmetric CFD model of the turbine blade flow field is established, and the temperature and pressure of the flow field are calculated and analyzed by the finite volume method. Then, the surface of the working blade is measured by scanning electron microscope. The morphology is observed to analyze the form of micro-defects on the blade surface. Finally, based on the results of simulation and experimental observations, the reasons for the blade defects and the factors affecting the changes of the blade surface microstructure are analyzed. The results show that the temperature of the leading edge of the blade reaches the highest ${860}\mathrm{\;K}$. Under the combined effect of geometric structure and wave system, the flow characteristics of the flow field near the leading and trailing edge, blade tip, and hub are complicated, and the temperature and pressure distribution in the flow channel is inhomogeneous. The hub near the trailing edge of the blade appears with a cross-grain/inter-grain mixed mode of microcracks about ${180\mu }\mathrm{m}$ in length, and an inclusion crack with a length of about ${30\mu }\mathrm{m}$ appears at the tip of the trailing edge. This is due to the thermal stress of the blade, the metallographic transformation of the blade surface, and the oxidation, hydrogen embrittlement and other effects. According to the actual task of the turbopump, the turbopump ground hot test program should be reasonably arranged, especially in the shutdown stage, consider whether to take atmospheric environmental isolation measures for the cooling of the turbine blades. The current work can provide a reference for the life evaluation of liquid rocket engine turbine blades.