In order to deal with modeling and simulation of load-sensing system, dynamic equations of variable pump, load-sensing valve, high-pressure relief valve and modulating cylinder of loadsensing system is established based on flow continuum equation and force balance equation. Then, steady state equations corresponding to low-pressure relief, high-pressure relief and load-sensing conditions are deduced by dynamic ones. Finally, loadsensing system is modeled and simulated through EASY5 software, whose parameters are identified using steady state equation of different conditions. Simulation results indicate that the load-sensing system model is stable and has a reasonable parameter set, which can simulate different conditions exactly.