<FONT face=Verdana>The nonlinear chirp of laser reduces the range resolution of synthetic aperture imaging ladar. The compensating algorithms by establishing reference path are developed. An equal delay theory to compensate nonlinear chirp phase errors and asynchronous trigged phase errors is proposed

including three methods: establishing matched target LO path

establishing reference path and twice coherent detection

establishing reference path and phase shifting calculation. The mathematical flow of the algorithm is established. The simulation of the airborne synthetic aperture imaging ladar model validates the feasibility. The characteristics of three methods are discussed finally.