Abstract: In view of the problems of traditional harmonic radar large signal leakage, high false alarm, low signal-to-noise ratio, poor detection ability of weak targets, strict electromagnetic compatibility design and complex system, the MIMO (Multiple-Input Multiple-Output) combined wave harmonic radar technology is proposed. The working principle of the MIMO combined wave harmonic radar is studied, the combined wave receiving method is used to replace the second harmonic of the traditional single-shot single-receive harmonic radar, the MIMO combined wave harmonic radar signal model is established, and the imaging principle and digital beamforming technology of the MIMO combined wave harmonic radar are studied. Simulation result shows that MIMO combined wave harmonic radar can effectively improve the isolation of the system and reduce the complexity of system design. Taking advantage of the multiple degrees of freedom of the MIMO radar, it effectively improves the ability of the MIMO combined wave harmonic radar to detect weak targets.