Abstract: The ellipsoid condenser is an important part of solar simulator. Light energy emitted from the light source can be collected and aggregated on the second focal plane, and the energy transmission efficiency is directly affected by this procedure. The efficiency of the energy collection procedure is determined by the ellipsoid condenser parameters. In order to increase the efficiency, the luminescence properties of xenon lamp were studied and the characters of the ellipsoid condenser condensation were analyzed by a model built in MATLAB. The ellipsoid condenser parameters such as the first focal length, the max imaging amplified ratio and the containing angle ranges could be determined after the study. The theory correctness was verified by 4 models built in Lighttools. The height of the light center determines the first focal length, the optical integrator F as well as the ellipsoid containing angles determine the max amplified ratio,and the containing angles should be 30～120, moreover the max angle determines the front hole diameter, the min angle and the radial adjustment of the light jointly determinate the back hole diameter. The ellipsoid condenser design can get theory support from the conclusions obtained in this paper, and the conclusions are helpful to accomplish a higher efficiency ellipsoid condenser.