Indium tin oxide （ITO） compound is widely used as the front contact of silicon solar cells. Its work function ΦITO is one of the most important factors related to the performance of solar cells. In this paper, we use the AMPS-1D （Analysis of Microelectronic and Photonic Structures） program developed by Pennsylvania State University to analyze the dependence of physical parameters of solar cells on the ΦITO. Our results show that ΦITO has greater effect on amorphous silicon solar cells than on the microcrystalline ones. Physical performance of amorphous silicon （the efficiency, filling factor etc.） improves with increasing ΦITO, which is more obvious than that for microcrystalline silicon. These results provide a useful guide in selecting appropriate p-type silicon materials based on the performance of front contacts.