Affected by the "marketized coal, planned electricity", more and more thermal power plants ara falling into the situation of deficit. However , the resource distribution our country determines that thermal power will still occupy an essential position in China’s electricity generation field in the near future or even longer time. As an important mean of the closed-loop management for investment, post evaluation for projects has become a key measurement in the decision-making stage. The paper comparatively analyze the use of post evaluation theory on 3 selected thermal power projects which are constructed simultaneously, mainly focusing on the power market factors that greatly influence the economic benefits of the projects. The analysis result will provide theoretical basis for subsequent thermal power project construction.