The invention provides a laser cladding structure of a steam turbine blade air inlet side. The problem that according to an existing steam turbine blade steam inlet side laser cladding slope structure, longitudinal sections are the same, so that cladding layers close to the blade tops on the blade longitudinal sections can be subjected to water erosion easily and lose efficacy can be solved. Accordingly, the anti-water-erosion capacity of a blade steam outlet side laser cladding layer is improved, and the service life of a steam turbine blade is prolonged. The structure comprises a laser cladding layer. A cladding slope which extends from the blade top to the blade root is formed in one side of the air inlet side of the steam turbine blade, and the laser cladding layer is arranged in the cladding slope in a cladding mode. The laser cladding structure is characterized in that the width and the thickness of the longitudinal section of the laser cladding layer are reduced gradually to zero from the blade top to the blade root, the length L of the laser cladding layer is 200 mm-900 mm, and the width and the thickness of the longitudinal section of the laser cladding layer are determined by the cladding slope structure.