The Life Cycle Assessment(LCA) is an international standard technique to assess the environmental aspects and potential impacts associated with products and services,using quantitative and systematic approaches. It has become an important supporting tool for environmental management and product design on an international level,being included in the series of ISO14000 standards for environmental management. This paper,using the LCA technique,conducts data-based research in the environmental load caused by energy power generation in various ways. It demonstrates comparative analysis with selecting three indexes of emission,pollution and energy consumption from thermal power,renewable energy and nuclear power generation in various ways,and to define the range of the clean energy power generation using normalized environmental load ratio. <<