To address the temperature gradient requirements for low-temperature soldering and high-temperature service，variable-temperature solders were developed，and the regulatory effects of Ni particle content on their properties and those of brazed joints were clarified. Using 4#SAC305solder powder as the base material，2-5 μm Ni particles and HP01high-activity flux were compounded to prepare Ni-based variable temperature solder paste. The effects of Ni content on the melting characteristics and wettability of the solder paste，as well as the growth of intermetallic compounds（IMCs）at the brazed joint interface and changes in shear strength during aging，were investigated. The results show that when the Ni content is 10%，the solder's melting point can rise to 227 ℃，with only a marginal increase observed after high-temperature storage. Wettability initially enhanced and subsequently decreased as the Ni content increased，resulting in a 60% reduction in the spread area observed at 20% Ni. The growth of the interfacial IMC layer corresponds well with the square root of the aging duration，achieving a thickness of 37.611 μm after 360hours of aging at 20% Ni. Under the same Ni content，shear strength decreases with prolonged aging，and under the same aging condition，it decreases with increasing Ni content. The solder paste with 10% Ni exhibitsminimal impact on shear strength due to aging，and its fracture surface displays a mixed ductile-brittle characteristic. The variable-temperature solder with 10% Ni content demonstrates the best overall performance，effectively raises the solder's melting point while exhibiting excellent stability during high-temperature service，thereby meeting the requirements for temperature gradient applications.