The effect of aging temperature on erosion-corrosion (E-C) behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on E-C behavior of 17-4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E-C test were observed by using scanning electron microscope (SEM). The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610 ℃, the hardness reached the highest value near the temperature 460 ℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows: pure erosion (wear) was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460 ℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed ε-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials. The effect of aging temperature on erosion-corrosion (EC) behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating EC apparatus. The effect of impact velocity on EC behavior of 17-4PH Surface micrographs of the specimens after EC test were observed by using scanning electron microscope (SEM). The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ° C to 610 ° C ° C, the hardness reached the highest value near the temperature 460 ° C. The characteristics of EC for 17-4PH stainless steels at different aging temperatures were as follows: pure erosion (wear) was dominant, corrosion was subordinate and at the same time corrosion erosion. The effect of aging temperature on EC rate of 17-4PH steels was not significant at low impact velocity, but it was found that EC resistance of 17-4PH s teels aged near 460 ℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed ε-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.