Abstract: Effects of different plating solutions permeating into fatigue crack tip on the crack growth rate of the 45 steel were investigated.The morphology and component of the fatigue crack tip after the solution permeating were analyzed by means of SEM and EDS.The results indicate that the crack growth rate of the 45 steel deposited with the two plating solutions was obviously lower than that of the one without deposition when the stress intensity factor amplitude ΔK was invariable.With the prolongation of time,the crack growth rate of the 45 steel after deposition first decreased then tended to be steady.The solution could effectively permeated into the fatigue crack tips.The crack arrest effect of the phosphate plating solution was better than that of the nickel plating solution.