In this paper， a method based on frequency group coding signal is proposed. Based on the linear frequency modulation （LFM） signal， the frequency group coding signal is constructed， which makes the pulse carrier frequency sequence of the transmitting signal a certain randomly. The anti-interference ability of the waveform is guaranteed. At the same time， a coherent processing method for the corresponding encoded signal is designed to address the issues of main lode broadening and side lode lifting problems caused by non coherent phase of frequency agile signals. Firstly， high-resolution distance compensation is applied to the compressed signal of the echo pulse， and then intra pulse coherence processing is achieved through velocity interpolation traversal and distance consistency correction. Finally， the advantages of the coding signal carrier frequency sequence are used to realize the intergroup coherent accumulation of the pulse group. In the simulation experiment， the coding signal of the building is verified compared with the advantages of LFM signal in the anti-interference， and the validity of the proposed method is compared to the sparse reconstruction algorithm based on compressive sensing.