For the pulse laser ranging system commonly used in flight target trajectory measurement, the variation of echo waveforms has significant effect on the ranging accuracy. In order to study the range error caused by the variation of echo waveforms,we analyze the echo characteristics of the complex three-dimensional flying target. Based on the typical Q-switched pulsed laser ranging, the mathematical model of transmitted pulse of Q-switched laser is analyzed, and a theoretical model is presented with echo power distribution calculated by the reflection characteristics, surface shape and orientation information of the flying target. On the basis of the above, the target model is built with a typical target, and the characteristics of pulsed laser echo are studied by simulation. The influence of target orientation on echo characteristics and echo distortion range error is analyzed. The pulse laser ranging experiment system is built and the simulated target is processed for verification experiment. The experimental results show that the echo pulse broadening and distortion range error caused by attitude angles variation of flight target are consistent with the basic theory, which verifies the effectiveness of the model.