A kind of array laser guide star (LGS) based adaptive optics (AO) system was independently proposed in purpose to overcome inherent problems in current wavefront sensing techniques. It can effectively eliminate focus anisoplanatism and improve its own wavefront sensing accuracy, drastically widen the scope of atmospheric turbulence that a LGS AO system can detect, and lower the requirement of an AO system for the brightness of LGSs. Its closed-loop working process was interpreted. Based on this working process, its simulation model was built and its wavefront sensing process was numerically simulated based on array LGS. At last, the accuracy of wavefront reconstruction was estimated and the errors of simulation was analyzed. Simulation results have shown that the accuracy of wavefront reconstruction is favorable and residual correction error is 11%, which invalidates the feasibility of using array LGS for wavefront sensing.