Abstract: In the field of security imaging, millimeter wave imaging has the advantages of high imaging resolution and low radiation energy, but there are also problems such as insufficient imaging ability for non-cooperative moving targets, large equipment size, and high cost. Therefore, a high-resolution non cooperative target millimeter wave imaging radar based on the multiple input multiple output (MIMO) system is introduced. Firstly, the radar system was designed, and antenna model and squint-range model were established. A one-dimensional MIMO linear array was designed, and a range-height two-dimensional resolution system was formed by using a large bandwidth signal. Secondly, the imaging processing algorithm is designed to compensate the coupling phase caused by the MIMO transmitting array and the target motion, and the two-dimensional image of the non-cooperative target is obtained by using the back-projection principle. Then, constraints on accumulation time were given to balance the different needs of capability accumulation and imaging of moving targets. Finally, radar imaging experiments were conducted to verify the imaging ability of the radar on metal objects obstructed by cloth, as well as on moving targets.