Abstract: Using the friction and wear testing machine and free abrasive wear testing machine, the wear resistance and wear mechanism of the low alloy high strength steels S700 and M700 with two different microstructures but same tensile strength level of 700 MPa were studied under different lubrication, loading and corrosion conditions; their wear mechanism were analyzed. The results show that the microstructure of S700 steel is ferrite and bainite, and the microstructure of M700 steel is ferrite and pearlite, and the hardness of S700 steel is slightly higher than that of M700 steel. Under the same sliding wear condition, the wear mass of S700 steel is less than that of M700 steel. The wear resistance of test steels under acidic condition is poor. Under the same corrosion wear conditions, the corrosion resistance of S700 steel is better than that of M700 steel. The sliding wear surface morphology of the steels is mainly micro cutting mechanism and plastic deformation mechanism; their corrosion wear morphology in acidic solution appears large area of corrosion pits and accompanied by spalling, and the morphology in alkaline solution is micro cutting, accompanied by a little peeling.