Abstract: Objective The purpose of the paper was to study effect of Zr content (wt.%) on microstructure and properties of Al-1.0Mg-1.0Si-0.5Mn alloy, so as to provide scientific basis for expanding application field of the alloy. Methods Microstructure and properties of Al-Mg-Si-Mn alloy with different Zr content were studied by SEM observation, tensile test, exfoliation corrosion test and fatigue test, and action mechanism of Zr element was analyzed to determine the optimal addition amount of Zr element in the alloy. Results Adding Zr to Al-1.0Mg-1.0Si-0.5Mn alloy could improve thickness of coarse grain zone of the alloy, enhance mechanical properties of base metal, and also improve strength and cyclic failure resistance of welded joints. When addition amount of Zr was 0.05%～0.10%, overall properties of the alloy were gradually improved. When addition amount of Zr was 0.10%, coarse grain zone of the alloy was the thinnest, size of Al(FeMn)Si compounds in the microstructure decreased, and Mg and Si phases in the bulk disappeared. Strength of base metal was increased by about 30 MPa, strength of welded joints was increased by about 40 MPa, strength coefficient of welded joints was increased by 0.054, median fatigue limit strength was increased by about 5 MPa, and performance of the alloy was improved comprehensively. When addition amount of Zr was 0.2%, the excess Zr interacted with grain refiner Ti in the alloy and aggregated to form a coarse compound with clear boundary with the matrix. This compound not only reduced effective solubility of Ti as heterogeneous nucleation core, but also led to grain coarsening and was easy to become a crack source for crack initiation, and deteriorated mechanical properties and corrosion resistance of the alloy. Conclusion Effect of Zr element on Al-1.0Mg-1.0Si-0.5Mn alloy was mainly reflected in refining recrystallized grains, effectively improving shape and size of refractory phase Al(FeMn)Si, but it was necessary to regulate addition amount of elements to avoid interaction with refined element Ti in the alloy, and reduce beneficial effect of alloy components.