In order to study the feasibility of a lever-type release mechanism of a fixed spherical rotor in a type of precision spherical motor and find out the optimal stiffness and preload force for the spring. Firstly ,this paper designed the structure of a lever-type release mechanism, then simplified the analysis model and finally conducted the dynamic simulation with different spring stiffness and preload force using the rigid dynamics analysis software ADAMS. The simulation results showed that the lever-type release mechanism could be leveraged to meet the target to fix spherical rotor, the optimal spring stiffness was 1.98 N/mm, and the optimal preload force was in the range of 4 ~ 5 N. Reasonable spring stiffness and preload could effectively reduce the impact force generated during the releasing process.