The invention discloses a method for improving thermal stability of alpha-L-rhamnosidase gamma-Rha1. The method comprises the following steps: taking a wild-type alpha-L-rhamnosidase gamma-Rha1 (WT) gene as a template, performing random mutation by an error-prone PCR method to establish a mutant library of the alpha-L-rhamnosidase, and establishing a 96-pore plate expression-inducing and high-throughput screening method to eventually obtain a mutant with improved thermal stability. A V529A mutant and the WT have the same tolerance to a metal ion and an effector which are used in a test. The mutant V529A has excellent enzymological properties; meanwhile, by the method provided by the invention, a mutant V529A-containing recombinant vector is successfully established, heterologous expression is achieved, and a good foundation is provided for industrial production and application of the alpha-L-rhamnosidase.