The invention discloses a radar two-dimensional constant false alarm detection method, a radar two-dimensional constant false alarm detection system, a radar two-dimensional constant false alarm detection device and a readable storage medium. The method includes the following steps that: OS-CFAR (Order Statistics Constant False-Alarm Rate) processing is performed on the distance dimension of a reference window shaped like a Chinese character '' tian'', so that the clutter power of each reference unit of the reference window shaped like the Chinese character '' tian'' in the distance dimensioncan be obtained; one kind of clutter power is selected from the clutter power of all reference units in each row of the reference window shaped like the Chinese character '' tian'' so as to be adoptedas the distance-dimension clutter noise power level estimation value of each row; and a Doppler dimension clutter noise power level estimation value is obtained on the basis of the distance-dimensionclutter noise power level estimation value of each row; a detection threshold value is obtained on the basis of the Doppler dimension clutter noise power level estimation value and a nominal threshold factor; and a unit to be detected is detected through the detection threshold value, signals which are lower than the detection threshold value are zeroed, and the real target of the unit to be detected is screened out. According to the radar two-dimensional constant false alarm detection method of the invention, the reference window is set to be the reference window shaped like the Chinese character '' tian'', and therefore, protection units and reference units can be reduced, a calculation amount is reduced, and precision is improved; the OS-CFAR (Order Statistics Constant False-Alarm Rate) and the CA-CFAR (Cell-Averaging Constant False-Alarm Rate) are combined, so that the target shielding phenomenon of the CA-CFAR under a multi-target condition can be avoided.