In the single point laser direct writing (LDW) process, there are some difference between the exposure dose distribution and the light intensity distribution, and the difference will bring the line profile errors. In this paper, the equations to calculate the exposure dose distribution for the polar coordinate and rectangular Cartesian coordinate laser direct writing system are presented. The difference between the exposure dose distribution and the light intensity distribution are discussed. The line profile on the photoresist after development is predicted. The experimental results agree well with the theoretical forecast.