Erosion-corrosion (E-C) experiments of 316L and two sigma phase reinforced Cr-Ni-Mo steels, S1 and S2, were conducted in 10 wt.% H 2 SO 4 +15 wt.% corundum sand to quantify the contributions of erosion, corrosion and their synergistic components to the total wear weight loss. The results showed that under severe E-C conditions, though increasing corrosion resistance was beneficial to decreasing synergistic weight loss rate, increasing erosion resistance by large amounts of sigma phase was more efficient to reduce the total weight loss rate of the steel. Therefore, the optimization of the balance between erosion and corrosion resistance to achieve the least synergistic effects between erosion and corrosion is a good way to develop the materials for slurry E-C resistance.