The erosion and corrosion resistance and behavior of the N80 steel in 3 . 5 wt . % NaCl and 10 wt . % solid particle solutions were investigated. The corrosion rate of the N80 steel was studied by weight-loss method, the macrography and micromorphology were observed, and the corrsion surface was analyzed by EDS. Based on the above the effect of pH valve on erosion and corrosion and mechansim of erosion and corrosion were studied. The results show that the corrosion rate of N80 steel decrease , with increasing pH values. And the corrosion mechanism are uniform corrosion when pH = 2 ,3 . And oxidation appears when pH value increases.