The non-uniformity distribution of UV light intensity in the imaging plane of integral micro-Stereolithography (µSL) System will induces serious distortion of object in building process, and the building accuracy of the SL system can not be assured. To obtain uniformity distribution of UV light intensity, experimental investigations were performed to research the relationship of UV light intensity with position (x,y) in the imaging plane and gray-scale z of the pattern in the integral µSL System. Based on the experiment results, the model of UV light intensity was established with least squares method. According to the model, for a given point in the imaging plane of the µSL system, the UV light intensity can be changed with varying the gray-scale of the pattern. As a result, Uniformity UV light intensity distribution is obtained in the imaging plane, and the difference between maximum and minimum value of UV light intensity is 0.06µW/cm2. The uniformity UV light intensity distribution provides a foundation for building accurate microstructures with the µSL system.