A method for manufacturing an oriented silicon steel product with high magnetic-flux density comprises the following procedures: 1) smelting and casting, wherein the oriented silicon steel is composed of, by weight, 0.035˜0.065% of C, 2.9˜4.0% of Si, 0.05˜0.20% of Mn, 0.005˜0.01% of S, 0.015˜0.035% of Al, 0.004˜0.009% of N, 0.005˜0.090% of Sn, 0.200˜0.800% of Nb, the rest being Fe; and after being smelted, molten steel is secondarily refined and continuous casted into steel slabs; 2) hot rolling; 3) normalizing; 4) cold rolling; 5) decarburization annealing; 6) MgO coating; 7) high temperature annealing: said sheets are firstly heated to 700˜900° C. and then secondarily heated to 1200° C. at temperature rise rate of 9˜17° C./hr and maintained at 1200° C. for 20 hr; 8) coating an insulation layer. According to the present invention, steel sheets can be fully nitrided during high temperature annealing, which can ensure a secondary re-crystallization to take place perfectly, thereby, the oriented silicon steel sheets with high magnetic-flux density can be achieved. The present invention solves the problem of nitriding that is encountered in production of high-magnetic-induction oriented silicon steel by the technique to heat steel slabs to a lower temperature.