In order to solve the difficult problem of predicting the fatigue life of the mechanism, obtain the high precision prediction method of fatigue life of rock tunneling machine supporting mechanism, ensure its work safety, the static strength analysis of the supporting mechanism under dangerous working conditions was completed by using Solidworks and ANSYS. On this basis, through the introduction of grey system model GM (1,1) to modify and improve the traditional Miner criterion, establish the grey Miner method to predict the fatigue life of the supporting mechanism. The results show that the grey system model GM (1,1) prediction accuracy can reach 91.375%. Compared with the actual fatigue life of the support mechanism, the relative error of grey Miner prediction method is only 5%, and the prediction effect is better than the traditional Miner method. It is proved that the grey Miner method is correct and feasible, and provides a new guidance for fatigue life prediction of rock tunneling machine supporting mechanism.