Adaptive radar target detector is a very important device in radar receiver. The objective of target detection is to maximize the target detection efficiency under the constraints of constant false alarm rate（CFAR）.Aiming at the problem that traditional two-dimension CFAR rectangular reference window has many reference units

large calculation amount and low detection efficiency in multi-targets environments

a new 2D "田" type reference window based on two-dimension rectangular reference window is designed

which eliminates some reference units of rectangular window that are not related to target detection decision. Experimental result proves that the detection efficiency is higher than the traditional 2D rectangular window.