Due to the unique nano pores and nadasi permeability of shale gas wells, high strength and large displacement fracture matrix fracturing with long sections and clusters, frequent pressure channeling interference, variable pressure and production mode and other factors, it is difficult to accurately predict its single well EUR. According to the three different periods of post fracturing, testing and decline of shale gas wells, the three-level calculation workflow of single well EUR is established by constructing estimation model and optimizing prediction method. In the post fracturing stage, the multiple regression relationship is used for preliminary estimation (The average calculation error is 5.5%), in the test stage, the linear relationship of test production is used for prediction (The correlation coefficient is 0.88), and in the decline stage, the calculation accuracy is mainly improved by analytical simulation method. Based on the dynamic and static data of WY block, EUR prediction is made for 140 shale gas wells. The results show that the average EUR of single well is 81 million cubic meter, 122 million cubic meter for class I well, 78 million cubic meter for class II well and 46 million cubic meter for class III well. This workflow and method can be used as a guide and reference for single well EUR calculation of other shale gas or unconventional gas.