The coupled multi-physical field environment in space, including vacuum, high-low temperature cycles, and temperature gradients, is the key factor affecting the life of the spacecraft’s rotary mechanism. Aiming at the use requirements of long-life space rotary mechanisms, this paper designs a multi-physical field accelerated life test scheme. This scheme simulates the vacuum environment, high-low temperature cycles, and temperature gradient conditions encountered during on-orbit operation. Ground-based accelerated life tests were conducted based on this scheme to verify the life of the mechanism under a comprehensive environment. Taking a certain type of space rotary mechanism as the test object, an integrated test platform was constructed, incorporating a vacuum simulation system, a temperature gradient control system, and a mechanism performance test system. Corresponding test procedures and failure criteria were established. Test results verified that after accumulating 130,000 ±7° small-angle reciprocating swings, the mechanism’s lifespan indicators met expectations. Post-test, the overall performance of the mechanism still satisfied the design requirements, with key moving components remaining in good condition. This study provides important experimental evidence for the on-orbit application of this mechanism type and offers valuable engineering reference for the design and evaluation of life tests for space mechanisms under multi-physical field coupling conditions.