Abstract: Aiming at trend towards integration of radar detection and electronic reconnaissance, a radio frequency digital radar receiver based on S-band active and passive integrative detection is designed by analyzing and designing each module in detail. This receiver works well on processing broadband signal even in cases that the optimal sampling rate is not fulfilled. Flexibility and probability of interception are guaranteed by its free switch between active probing and passive reconnaissance. Furthermore, as the design is based on integration of parallel and polyphase structure which reduces the overall resource consumption, real-time signal processing can be achieved easily. Experiments and tests on simulation data and hardware platform verify the effectiveness and efficiency of proposed design.