6A02 aluminum alloy sheet was widely used in helicopter， sometimes milling need to be carried out. By means of dimension measurement， tensile property detection and metallographic analysis， the influence of chemical milling on the thickness， surface quality， mechanical properties and microstructure of 6A02 aluminum alloy sheet was studied. The results show that chemical milling can thin the thickness of aluminum sheet. The combined effect of Na₂S and triethanolamine in the solution can reduce the galvanic corrosion effect of alloy elements and Al， and the surface quality of the thin plate is improved. The electrochemical properties of the precipitated phase of the alloy are not significantly different from the matrix， and will not cause intergranular corrosion defects of the alloy， and have no obvious effect on the mechanical properties and microstructure of the sheet. 6A02 thin aluminum sheet can be processed by chemical milling.