The work aims to explore the effect and mechanism of the new process of shot peening pretreatment of 38CrMoAl and multi-element rare earth ion penetration strengthening. The optimum treatment process was selected by orthogonal experiment. Contrast test under the optimum process parameters selected. The surface hardness and thickness of each sample after nitriding were measured, and the metallographic structure was observed. The performance and causes of nitriding layer of each sample were studied by SEM, energy spectrum analysis and phase analysis. The optimal process parameters of 38CrMoAl steel shot-peening pre-treatment and rare earth osmosis plasma multi-elements penetrating process were insulation temperature 540 ℃, ammonia flow rate 2.0 L/min, and holding time 9 h. The maximum hardness of the 38CrMoAl steel specimen was 1221HV, and the thickness of the layer was 355 μm. The metallographic microstructure of 38CrMoAl steel samples shows that shot-peening pre-treatment and rare earth leaching promote the plasma multi-elements penetrating. The multi-elements penetrating effect of the composite process is greater than that of single rare earth osmosis and plasma multi-element. The results of EDS of 38CrMoAl steel samples show that the content of nitrogen, carbon and oxygen elements and the depth of infiltration layer in the composite treatment process are significantly higher than that in the single treatment process. The shot-peening pre-treatment and rare earth catalytic plasma multi-element penetration process is superior to common multi-element penetration and Rare Earth Multi-element penetration. The composite treatment of shot-peening pre-treatment and rare earth can significantly enhance the thickness of penetrating layer and the content of penetrating elements, which is conducive to the improvement of material surface properties.