Spaceborne full waveform laser altimeter for space remote sensing has the advantage of high precision and more information. Simulation and analysis of spaceborne full waveform laser altimeter have become a valuable tool for system design and evaluation. Modules of simulation have been proposed according to research on spaceborne full waveform laser altimeter. Transmitter model, target model and receiver model are established for simulation of full waveform echo signal. Full waveform data are simulated using a square sampling process taking no account of influence of atmosphere and difference of reflection. Moreover full waveform data are processed for parameter calculation. Laser echo calculated by each module will be estimated before system design which is useful for system design and full waveform data process.