The invention relates to a method for improving the magnetic performance of copper-containing oriented silicon steel. The method comprises the steps that S1, steel making, secondary refining and continuous casting are conducted, and then a plate blank with the following components including, by weight, 0.040%-0.055% of C, 3.00%-3.40% of Si, 0.1%-0.30% of Mn, 0.006%-0.030% of ALs, 0.4%-0.7% of Cu, 0.006%-0.012% of N, smaller than or equal to 0.025% of S and the balance Fe and inevitable impurities is obtained; s2, the plate blank is subjected to hot rolling and primary cold rolling; s3, after primary cold rolling, performing decarburization annealing under the protection of a nitrogen and hydrogen wet atmosphere with the temperature of 800-900 DEG C and the ratio of hydrogen partial pressure to water vapor partial pressure of 0.2-0.5, so that the oxygen content in the copper-containing oriented silicon steel is 700-900 ppm; s4, carrying out secondary cold rolling after decarburization annealing, and then carrying out cold coating of a magnesium oxide separant; and S5, after cold coating of a magnesium oxide separant, high-temperature annealing, discharging, stretching, flattening and annealing are carried out. According to the method for improving the magnetic performance of the copper-containing oriented silicon steel, the magnetic induction intensity B8 of the copper-containing oriented silicon steel is not smaller than 1.9 T, the magnetic performance of the copper-containing oriented silicon steel is improved, the profit per ton of steel is increased, and the application range of the copper-containing oriented silicon steel is widened.