This paper firstly describes some techniques of space-borne SAR raw signal simulation, including satellite-ground space geometric model, space-borne SAR raw signal mathematic model and RFPC algorithm. Based on these techniques, a method for space-borne SAR raw signal simulation is presented and the simulation flow is given in details. After the parallelizability analysis, the simulation method is parallelized with parallel programming tool OpenMP. Simulation results prove that the parallel simulation method is correct and effective.