Abstract: A new method of lofty target detection which based on channel-level STAP was proposed for missile-borne wideband mono-pulse phased-array radar. The idea of our method is to analyze the range-height and Doppler-height coupling effect of lofty target on sea plane. It carries on range-Doppler imaging of sum channel and delta channel first. Then, the adaptive cancellation technique is used to suppress the clutter. And the modified sum channel and delta channel are formed by digital processing. Finally, the target detection and target angle measurement are carried out by using the modified sum channel and delta channel. Theoretical analysis and simulation results show that the presented method can suppress clutter and improve the performance of lofty target detection effectively. Besides, it has low computational complexity.