A comprehensive physical model describing the dependence of the steering performances on the various physical parameters of a liquid crystal optical phased array (LCOPA) is proposed. Then several typical factors affecting the steering performances of the LCOPA are investigated. The quantificational computation and simulation of the influence factors are discussed in details, the relationship between key performances of LCOPA with the influence factors are analyzed numerically, and the optimization methods are conducted based on analysis results. Finally, the experimental results of laser are compared with the simulation results based on the comprehensive model, the simulation far-field diffraction patterns are basically accord with experimental photographs.