Life cycle assessment systems of wind, PV and coal-fired power generation were established based on life cycle assessment theory, so as to compare and analyze their environmental load produced at different stages. Results show that in the construction state of a power plant, the carbon footprint of coalfired power generation is 1.94 g/(kW · h), which is the lowest in the three power generation ways, and the carbon footprint of wind power generation is 9.42 g/(kW · h),which is the highest. Whereas in the operation stage of a power plant,the carbon footprint of PV power generation is almost zero, and that of wind and coal-fired power generation is respectively 0.2 g/(kW · h) and 83.3 g/(kW · h),indicating that coal-fired power generation produces the highest carbon footprint. The ratios of carbon footprint in construction stage for wind and PV power generation are relatively high, which are 99.4% and 99.78%,respectively; while the ratio of carbon footprint in operation stage for coal-fired power generation has the highest value of 96.13%. Results also indicate that coal-fired power generation has the greatest influence on global warming in a whole life cycle with a standard equivalent of 3.63 * 10~(-5),while wind power generation has the least influence with a standard equivalent of 7.9 * 10~(-7); whereas PV power generation has the biggest impact on environmental acidification with a standard equivalent of 6.7*10~(-6),and wind power generation has the smallest impact with a standard equivalent of 1.6* 10~(-7). The emission of solid waste is almost zero in both wind and PV power generation.