Abstract: In order to save test costs while ensuring accurate and reasonable research on the reliability performance of wind turbine main shaft bearings, this paper proposes a similar criterion for life test based on scaled-down models. Firstly, this article clarifies the process method of applying similarity theory to solve similarity criterion and conduct simulation verification; secondly, based on physical quantities such as the life influencing factors of wind turbine main shaft bearing and the condition parameters of bearing life test, the similarity criterion of equivalent life model is obtained by dimensional analysis; Finally, the finite element simulation of the linear contact single roller model by ABAQUS software and FE-SAFE software verifies the correctness of the similar criteria.