The effect that the intensity of the writing spot relating to the amounts of defocus in the laser direct writing photolithography is analyzed based on the diffractive theory 'and the ray-tracing method, respectively. The photolithographic experiments with various amounts of defocus are developed by using four-axis laser direct writing system, which agree closely with the results of the theory or the ray-tracing method. The grating and reticle fabricated by this way are measured with atomic force microscope (AFM).