This paper analyzes the impact of id and iq on the output torque and speed of PMSM, and optimizes the current loop by improving the feed back input id and iq. An adaptive filter is designed for filtering the current which is translated from ia, ib and ic. Compared to the traditional FIR filter, this algorithm is more concise. And the convergence coefficient μ which could be changed online can adjust the convergence speed of this algorithm. At last, the experiment proved that this method can reduce the noise and improve the output current of PMSM. This system is more stable and its response speed is faster. ©, 2014, Diangong Jishu Xuebao/Transactions of China Electrotechnical Society. All right reserved.