The spectral test of solar simulator is carried out. The test result shows that the energy of the spectra from 800 to 900 nm and from 900 to 1100 nm which are radiated by the xenon lamp from solar simulator without laying optical filter occupies too much percentage of the whole spectra and is greater than that of the international standard code matching limit. Then it results in that the relatively spectral distribution of energy cannot fulfil the demand of A or B grade, which seriously affects the solar cell test result. So solar simulator needs to lay special designed optical filter to remedy the spectra, and the optical filter can filter or weaken energy of infrared band and fulfil the spectral demand of A or B grade. By optimal design of optical filter, we can make the spectrum to reach optimal uniformity.