Abstract: Objective To improve the reliability of tensile strength of 7075 aluminum alloy welded joints, an IRSM based optimization design method for the reliability of tensile strength of 7075 aluminum alloy welded joints is proposed. Methods Firstly, based on finite element theory and welding test platform, the effects of spindle force on welding temperature and joint tensile strength are analyzed separately. Secondly, based on simulation and experimental data, a response surface model for temperature and tensile strength of welded joints is preliminarily constructed, followed by an optimization model for the response surface of welded joints. The optimization algorithm is used to reconstruct the improved response surface model of welded joints. On this basis, based on the optimal test sample data and reliability optimization principles of joints, a reliability optimization model for welded joints is constructed. Multi-objective optimization algorithm and the principle of minimizing the principal axis force in three directions is used to complete the Pareto optimal solution screening. Finally, a study is conducted on the reliability optimization of tensile strength of 7075 aluminum alloy welded plates. Results The research results indicate that when the welding parameters are 1 500 r/min and 140 mm/min, the optimal tensile strength of the joint is 406.5 MPa. After optimization, the reliability of the joint tensile strength reaches 97.5%, while the maximum welding temperature decreases to 302.5 ℃. Conclusion This conclusion can provide reference value for improving the quality of 7075 aluminum alloy welded joints.