In order to flexibly adjust the energy at each frequency of the time domain filter and improve the performance of airborne radar to suppress clutter and interference signals by using prior knowledge, this paper proposes a time domain filter design algorithm based on prior knowledge of dimension reduction adaptive processing. Firstly the prior knowledge and conventional direction finding and ranging methods are combined to estimate the clutter power spectrum and the interference. Then, the information is used to design the gain of each frequency region of the dimension reduction processing. Finally, convex optimization idea design optimal time domain filter. The result show that the time domain filter designed in this paper distributes the energy of different regions to ensure the formation of deep and wide notches at the ground clutter and interference Doppler region, which not only suppresses ground clutter, but also improves the suppression in the main clutter region. These greatly improves the ability of airborne radar to detect targets in complex environments.