CdS works as window layer in CdTe/CdS film solar cells.Interdiffusion at the CdTe/CdS interface is believed to have significant influence on device performance.In this work,Te doped CdS films were prepared by Te and CdS vacuum co-evaporating.X-ray diffraction(XRD)peaks of CdS films shifts to lower angles as Te concentration increases,which supports that Te enters CdS lattice,taking S site.Raman spectroscopy also show the precipitation of excessive Te.Transport and optical properties were also studied.