The invention discloses a laser cladding method for an abrasion-resistant anticorrosion coating of a water turbine unit runner. The method is characterized by comprising the following steps of: performing surface cleaning on greasy dirt and rust layers on the surface of the water turbine unit runner; then selecting iron-based alloy powder, making the alloy powder discharged from an automatic powder feeding head fall into a laser molten pool by adopting laser equipment and an adjustable automatic powder feeding device, adjusting the powder feeding amount, and forming uniform and dense laser claddings on the processing surfaces of the upper and lower coronal planes, wherein the thicknesses of the laser claddings reach 0.2 to 1.8 millimeters; and finally, checking the processing parts of the upper and lower coronal planes of the runner by using a dye penetrant inspection method, wherein the processing parts are required without defects of cracks, air holes and the like. The laser cladding coating is uniform and dense, forms firm metallurgical bonding together with a matrix, has good abrasion resistance and anticorrosion performance, and can remarkably improve the abrasion-resistant and anticorrosion performance of the water turbine unit runner and prolong the service life of the water turbine unit runner.