Abstract: The erosion corrosion behavior and mechanism of 35CrMo steel in guanidine gum solution, sand water solution and sand guanidine gum solution were investigated by weight-loss method, microstructure observation, and the electrochemical method. The results showed that the descending order of solution erodibility was as following:sand guanidine gum solution, sand water solution and guanidine gum solution. Guanidine gum added into the sand water solution could reduce erosion corrosion. The corrosion current density of 35CrMo steel was higher in the sand guanidine gum solution than in the guanidine gum solution, indicating that the presence of sand can significantly raise the corrosion increment caused by mechanical action.