The deformation compatibility equations and the torque balance equations of a star gearing with three branches are estabished based on the characteristic that the system composes a closed-loop of power flow.In consideration of the parts manufacturing errors,assembly errors,bearing stiffness and float,the power splitting coefficient of each star gear and the system are calculated by using the theory of equivalent mesh error.The relation between the errors,float and the bearing stiffness and power splitting are analyzed from the perspective of statics,and comparing with planetary transmission.A new algorithm is proposed,the reference for the engineering application is provided.