Aiming at the influence of high acceleration modulation of LFMCW radar echo signal in the short range and high resolution applications on missile, satellite, and plane, we derived the expression of acceleration resolution for Linear FMCW (LFMCW) signal. It is concluded that the acceleration resolution is inversely proportional to the square of the effective time width. We also analyzed the influence on the Doppler resolution and time delay caused by the unknown acceleration. It is concluded that the increase of time width doesn't necessarily enhance the Doppler resolution because of the exist of acceleration, delay resolution decrease with the increase of unknown acceleration. Computer simulations justified these conclusions.