A colouring method for wrought aluminium alloy welded joint colour metallography, comprising pre-etching and colouring, wherein the pre-etching comprises an acid etching processing step. The acid etching processing is as follows: an acid etching solution is heated to 55° C.-65° C., dripped onto a test piece surface for 50 s-60 s, then flushed with a large amount of deionized water and dried with hot air. The acid etching solution is an aqueous solution comprising 0.3-0.5 mol/L of Cl−, 1.4-1.8 mol/L of H+ and 0.3-0.5 mol/L of PO43−. The colouring is as follows: the test piece subjected to the pre-etching processing is completely immersed in a Weck's reagent, shaken slightly for 5-10 s, flushed with a large amount of deionized water after surface colouring and dried with hot air.