An innovative parallel laser direct writing system based on intensity modulating spatial light modulator(SLM) is proposed,and the math model about this system is established.The simulated results about this system are given in the condition of taking manufacturing blazed grating as example.The investigation shows that this novel system can fabricate binary optical elements with sub micron minimum feature size,and has intrinsic parallel characteristic owing to its stepper exposure mode,therefore it can improve the writing velocity at large.The binary optical elements fabricated by using this system are similar to continuous profile elements,and more than 80 % diffraction efficiency is achieved.