Continuing increase of the Chinese economy,accompanied by decrease of energy intensity,has aroused suspicions about the authenticity of the data of Chinese economy growth and energy consumption.Thus,it is significant to research the changes and trends of Chinese energy intensity.By far,however,few works of quantitative research have been made on how the changes of Chinese economic structure influence the changes of energy intensity.This thesis analyzes the changes and trends of Chinese energy intensity,illuminates that these changes and trends are basically consistent and reasonable.Moreover,based on the analysis,the thesis divides the change of energy intensity into structure share and efficiency share,puts forward their formulations,and quantitatively analyzes the structure share and efficiency share of the change of Chinese energy intensity.According to the analysis,decrease of Chinese energy intensity from 1998 to 2000 was mainly due to the increase of energy utilizing efficiency of the Primary,Secondary and Tertiary Industry,among which decrease of energy intensity of the Secondary Industry predominantly led the fall of the whole energy intensity.