Based on the comprehensive analysis of climate factor, biological feature and soil humility as well as the experimental data of aspen shelter belt for years, a calculation model for aspen shelter belt evapot ranspiration in the Tarim River basin was built and verified with the evapot ranspiration data directly measured in aspen shelter belt. The result revealed that the model had high precision and could be used to calculate the evapot ranspiration in aspen shelter belt of the Tarim River basin.