A method for rigidity enhancement and weight reduction using laser peening, includes the following steps: determining a limit size of a component; performing laser peening strengthening test on the component, and setting multiple groups of strengthening parameters; performing material performance test on the component, and acquiring material performance improvement data; determining a topological optimization strengthening region; optimizing the cross-sectional size of the component according to the material performance improvement data; and estimating static/dynamic strength, rigidity, bearing capacity and reliability indexes of the optimized component, judging whether design requirements are met or not, and repeating the step of determining the topological optimization strengthening region if NO, or completing the design of the component if YES.