The Investigation of pulse ranging signal for pulse coherent laser radar is presented. On the basis of the calculated pulse waveform of Q-switched laser, the waveform of pulse laser heterodyne and its frequency spectrum of Fourier transform reflected from scattered treflection object are studied theoretically. Experimental studies are made on reflected pulse laser heterodyne of tunable electrooptically Q-switched CO 2 laser and its frequency spectrum of Fourier transform. In addition, the objected range is calculated. The experimental results are consistent with the theoretical analyses.