Using the Community Atmospheric Model Version 3.1 (CAM3.1) of NCAR, the influence of greenhouse gas, global sea surface temperature (SST), solar constant, and volcanic activity on surface temperature is studied. The results show that increase of greenhouse gas and global SST contributes to the warming trend. Over recent 100 years, annual surface temperature in China undergoes two decadal oscillations and increases. China experienced two warm-periods during 1940s and 1990s respectively and two relative cold periods during 1910s and the period of 1950s-1960s. The variations of surface temperate over China, solar constant and SST have an oscillation period of 60 years, two decadal oscillations of surface temperature over China are induced by two decadal oscillations of solar constant and SST, the variation of surface temperature lagged behind of solar constant and SST. The volcanic activities before 1920s and after 1960s are one of the reasons of cooling trend during 1910s and 1960s-1980s.