Abstract: Plasma sprayed Fe-base WC cermet coating on 45 steel matrix was strengthened by using high temperature assisted ultrasonic rolling technology. The surface morphology, roughness, cross-section structure morphology, phase composition and microhardness of the coating treated by ultrasonic rolling without ultrasonic rolling, ultrasonic rolling at normal temperature (0.4 MPa, 25 ℃) and ultrasonic rolling at high temperature (0.4 MPa, 600 ℃) were studied. The results show that, compared with samples without ultrasonic rolling treatment and normal temperature ultrasonic rolling samples, the high temperature assisted ultrasonic rolling surface strengthening technology can better realize the plastic deformation of the material, and better promote the healing of the microscopic cracks on the surface of the material, and the compactness of the cross-sectional holes is better, the bonding state of the 45 steel substrate/coating is improved, and the surface roughness of the coating is further reduced. The Ra is reduced from 1.24 μm of plasma spray to 0.12 μm. At the same time, on the subsurface, a deeper nanostructure hardened layer is formed. The grain size obtained by this process is the best to be refined, reaching 50 nm, and the surface microhardness is increased from 615 HV to 1150 HV, the microstructure and properties of the coating is further improved.