Abstract: This paper presents a novel space time adaptive prewhitener for reverberation based on a two-dimensional autoregressive model.The space time adaptive prewhitener jointly processes received data in angle and Doppler to improve the separation of a target from reverberation.It is more effective than the traditional methods which process data in angle and Doppler separately.The detector using the space time adaptive prewhitener is shown to yield a gain of 9~11 dB in detection than previously one dimension autoregressive prewhitener when operating in a reverberation background containing target echoes.