Uniformity is an important index of the solar simulator, and the ellipsoid condenser plays an important role in solar simulator. Light energy emitted from the light source can be collected and aggregated on the second focal plane, and Gaussian energy distribution is formed by using the ellipsoid condenser. The uniformity of the irradiated surface is directly determined by the distribution. A deformed ellipsoid condenser is obtained through ellipsoid equation Taylor expansion. The surface of the condenser can be deformed by 3 coefficients. The energy distribution on the second focal plane can be improved by the deformed ellipsoid condenser, and the uniformity of the solar simulator can be enhanced because of the weakened light energy contrast. An ellipsoid condenser used in a project is deformed and the deformed ellipsoid curve is obtained by using Matlab. The uniformity improvement on the second focal plane is proved by the simulation results of LightTools.