In recent years，the asynchronous motor drive of indirect field- oriented control （IFOC）is widely used in high performance drive systems because of its high efficiency，high stable performance and power factor. In this paper，the IFOC technology is used to control the size of the speed of asynchronous motor，and the Z- source inverter is used，namely putting a pair of LC network in front of the inverter main circuit，to achieve the function of boost or buck the voltage and improve the efficiency of asynchronous motor by controlling the direct duty ratio.