Bearing electrical erosion caused by circulating bearing current exists in the high-power induction motor, which affects the safety of drive system. This paper presents a theoretical analysis of the generation of circulating bearing current based on electromagnetic field theory. 2D finite element analysis is adopted to calculate the parasitic capacitance and loop current method based electrical network theory is used to analysis the distribution of the common mode current. A new and reasonable circulating current equivalent circuit is built up. A 300kW induction motor fed by PWM inverter is simulated with MATLAB /SIMULINK software and the circulating bearing current of the motor is calculated.