According to the requirement of terahertz wave scanning imaging system, the position closedloop controlled X_Y scanning stage was realized on the basis of the stepping motor and screw nut transmission mechanism by adding a grating ruler.PC and motion control card were taken as the core of the control system. The function modules of the scanning control software such as scanning parameter configuration,scanning path generation, motion control, fixed and continuous motion were realized by using VC++6.0 language and function library.The experimental results show that the scanning stage is stable and reliable, and the positioning error is less than 0.05 mm which meets the requirements of THz imaging scanning.