The invention provides an adjustable fixture for laser cladding of steam turbine blades. The adjustable fixture is capable of solving the problem that an existing blade fixture, when applied to laser cladding of blades, is incapable of meeting deformation control requirements of the blades. The adjustable fixture comprises a support; a blade root positioning hold-down structure and a blade tip center structure are mounted at two ends of the support, respectively; the blade tip center structure comprises a center support and a center; the center support is mounted on an inner-side end face of the support and the center is mounted on the center support; the adjustable fixture is characterized in that: a blade cladding region profile enclasping structure is further mounted on the support, and comprises a profile clamping supporting plate and cylinder clamping assemblies; the profile clamping supporting plate is movably mounted on the support; at least two key grooves parallel to each other and extending in full length in an X direction are formed in parallel in the profile clamping supporting plate, and the cylinder clamping assemblies are arranged in pairs and oppositely in the key grooves; and therefore, each pair of cylinder clamping assemblies enclasps a cladding region profile of a blade from inside arc and back arc sides of the blade.