Influence of environmental temperature and the temperature difference between the front and back surfaces of the cell on the output parameters of a typical commercial c-Si solar cell is analyzed by two-dimensional finite difference method. The results show that even for the cell with its front and back surfaces at the same temperature, the temperature distribution in the cell's interior is not homogeneous; the temperature difference between the front and back surfaces will generate a temperature gradient inside the cell; the temperature variation in the cell's interior for both the front and back surfaces at the same and different temperature can be divided into two regions; considering three heat mechanisms related with carrier transport process, Peltier and Thomson effects and Joule heat effects have more important influences on the temperature; with environmental temperature increasing, the values of open circuit voltage, fill factor and efficiency will all decrease and those of short current will increase; with the temperature difference increasing, the values of |Jsc| and FF will decrease, but those of Voc and will increase.