Simulation is an effective method to evaluate the performances of existing laser imaging systems and to develop novel laser imaging detection technologies. The characteristics of laser pulse returned signals and the establishment of the related models are of vital importance for the echo signal processing and the laser imaging simulation. This paper studies the modelling procedure of the returned signals based on the laser transmitted pulse model, and the modelling method for target scattering properties based on the unit impulse response is discussed in detail, to deveop detection algorithm models. The simulations of 3D laser imaging based on linear array scanning in the pushing-broom are carried out by means of arraying the single return detection. The results show that the laser imaging simulation can yield the simulated images effectively under a wide variety of conditions.