Abstract: Modern radar system relies heavily on DSP to achieve high levels of system performance and flexibility. It is developing trends to put the analog to digital conversion for radar antenna element as close as possible to the antenna. The technology advances on high speed ADC and DSP promise to allow digital techniques to be used at RF. The key techniques in the study on digitized receiving subsystem at RF is described in the paper. The design simplified the receiving subsystem and reduced the nonlinear distortion.