A new dynamic exposure model was proposed to predict the laser direct writing quality in Cartesian coordinate exactly.By considering the effect of photoresist absorbing beam energy,the Gaussian distribution of writing beam and the dynamic exposure process,numerical simulation results indicate that when the incident laser beam is shape of constant Gauss,the results obtained by proposed model agree well with that by Dill model under equivalent conditions.The model makes up the shortcomings of the traditional models and can be taken as an appropriate solution to the dynamic exposure process.Based on the model,the influences of the direct writing power and velocity on the profile of writing line are also analyzed,which can be considered as an effect analysis method for optimizing the parameters of laser direct writing.