Three different types of laser radars are introduced based on the ranging principle of FMCW(frequency modulated continuous wave) laser radar,and also the ranging procedure is deduced.The laser ranging simulation platform is set up for sawtooth,triangular and sine modulated wave.Based on this platform,the modules for signal generation and beat signal simulation are designed and the frequency is measured from the beat signal.In the end,the application conditions for three different kinds of FMCM laser radars are analyzed,which provides the reference for the selection of system and hardware design.