Abstract: Discloses a coherent microwave photonics radar detection method and system based on injection locking frequency multiplication. The method uses a baseband signal to modulate an optical carrier to generate a modulated optical signal including a plurality of high-order sidebands; the modulated optical signal is divided into two paths which are respectively injected into two slave lasers for high-order sideband injection locking to obtain two locked sideband optical signals; Based on combining and splitting two locked sideband optical signals, the radar transmitting signal and receiving optical signal can be obtained through photo-detection and electro-optic modulation. After coherent detection of receiving optical signal, obtaining the intermediate frequency signal, and detection target information can be extracted from intermediate frequency signal by radar algorithm.