Taking into account the film layer thickness and silicon impurities of amorphous silicon solar cells with the nip-type[ITO/a-Si (n)/a-Si (i)/ a-Si (p)/Al] structure, the conversion efficiency, fill factor, and open circuit voltage of the nip-type amorphous silicon solar cell are numerically analyzed and discussed. The results show that the short circuit voltage, conversion efficiency, and open circuit voltage increase as the thickness of p-type layer increases. With the increase in the thickness of intrinsic layer, the spectrum characteristics for the short wavelength range becomes worse and the quantum efficiency degrades. When the thickness of n-type, intrinsic, and p-type layers are 5 nm, 5 nm, 10 μm, respectively, the conversion efficiency gets to 9.728% for the donor impurity concentration of 1.5×1016 cm-3 and the acceptor impurities of 2.5×1019 cm-3.