As the political, economic and cultural center of China, Beijing is facing worse CO2 emission influences than other cities. Therefore, digging out the influence factors of CO2 emission is valuable for maintaining Beijings sustainable development. This paper discusses the driving forces influencing Beijings CO2 emissions based on Path-STIRPAT model-a method combining Path analysis and STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The analysis shows that GDP per capita (A), industrial structures (IS), population (P), urbanization level (R) and technology level (T) are the main factors influencing Beijings CO2 emissions. The sequence of the size of factors direct influence on Beijings CO2 emissions isA>IS>R>T>P, while that of factors total influence isA>R>P>IS>T.