Semitransparent CdTe solar cell is a promising technique for the development of ultrathin CdTe photovoltaics, which can not only be used as architectural components of window, fence or roof, but also allows a bifacial structure or tandem configuration to improve sunlight utilization. In this work, the ultrathin polycrystalline CdTe is prepared by sputtering and semitransparent solar cells with a structure of glass/FTO/SnO2/CdS/CdTe (similar to 920 nm)/CuCl/ITO are fabricated. The CdCl2 post treatment was conducted on sputtered ultrathin semitransparent CdTe by varying the CdCl2 treatment amount. The effects of the CdCl2 treatment amount on the microstructure, optical property of ultrathin CdTe films, and the performance of semitransparent CdTe solar cells were extensively studied. By optimizing treatment amount, a front illuminated efficiency of up to 9.74% was achieved. Furthermore, the completed solar cells exhibited excellent near-infrared transmittance of similar to 70% in the wavelength range of 850-1100 nm, which strongly supports the future application of semitransparent CdTe solar cells in building integrated photovoltaics or tandem configurations.