The CdTe thin film solar cells with the structure of ITO/ZnO/CdS/CdTe/Au were irradiated by 1.6MeV high-energy electrons with the fluences from 5×1013/cm2 to 1×1016/cm2. The characteristics of devices before and after irradiation were studied using dark current-voltage (I-V), capacitance-voltage (C-V) and admittance spectroscopy (AS) measurements in the temperature range from 303K to 353K. The results are shown that the diode ideal factor and dark saturation current for irradiated devices first decrease and then increase significantly with fluences from 5×1013/cm2 to 1×1016/cm2, meantime the effective carrier concentration at room temperature of CdTe absorbing layer increases first and then decreases. The carrier transport mechanisms in CdTe solar cells are analyzed before and after irradiation. The non-irradiated devices and irradiated devices with fluences less than 5×1014/cm2 are dominated by the recombination current of electron-hole pairs in the depletion layer. However, it is dominated by the recombination current of tunneling at the interface after the irradiation of higher fluences. The changes of types and amount of defects caused by electron irradiation are the major reasons for the above mentioned variations.