As the fatigue life of tower crane is influenced by many uncertain factors, in this paper, the Grey System Theory is used to forecast the fatigue life of the tower crane. The model of GM ( 1,1 ) and the power model of GM ( 1,1 ) are respectively used to the prediction of fatigue life of lifting arm of QTZ630 under the load spectrum of actual conditions. It is shown that the life prediction error of the traditional Miner method is 43.7% ; and the error is decreased to 25.2% by using linear gray model of GM( 1,1 ) ; while the error based on the non-linear gray power model of GM( 1,1 ) is dropped to 23.2%. The life prediction result based on gray prediction method is inclined to safety, which indicates that the grey prediction offers a way to predict the fatigue life for tower crane. And it also have appropriate prospect in the life prediction field of tower crane for the high prediction accuracy and reliability.