In this research, the CdTe polycrystalline films are prepared at various temperatures by close-spaced sublimation. The experiment was conducted to investigate how difference in preparation temperature effects on CdTe/CdS solar cells by the characteration of I-V,C-V curves and deep level transient spectroscopy. The result shows that the difference of temperatures has some effect on Isc and FF, but not on Voc. The samples prepared at 580℃ have lowest dark saturated current density, higher carrier concentration and the photovoltaic performance is preferable. The response of deep-level impurities in CdTe films is unchanged with temperature and frequency, but the sample prepared at 580℃ has less deep-level impurity recombination because of lower hole trap concentration. Then, the CdS/CdTe solar cells with large area of 300 mm×400 mm have efficiency reaching 82% by improving the uniformity of temperature field.