With the increasing seriousness of climate change problem, carbon footprint has become a very useful method to measure carbon emissions and has been widely accepted. In modern industry, electricity is almost consumed in all industry processes, and electricity is the first "footprint" of most products. As carbon emissions is always measured by theoretical estimation from input inventory but not experimental data, the input inventory of electricity generation becomes very important in carbon footprint analysis. Electricity generation is a very complex process, where all input items inter-dependant on each other and the whole system is an infinite cycle net. But in the traditional calculation model of input inventory, the interaction effect of production system is usually neglected. The major work of this study is to make clear the carbon emissions of provision 1kWh thermal power generation to consumers in China in 2006, since thermal power generation takes the most proportion of Chinese electricity. This study used a matrix-based model which includes interaction effect of the system to calculate the input inventory of electricity generation, and then the carbon emissions of thermal electricity generation in China in 2006 can be calculated. The final result of this paper can be used in carbon footprint, Life Cycle Assessment or some other related fields.