The invention discloses a forging method for a main pipe blank with branch pipe nozzles used in a nuclear power station, comprising following steps: firstly, rolling the ingot body of a forged piece, pressing the ingot to form a clamping handle; secondly, upsetting the ingot; thirdly, drawing out the ingot, and determining the directions of the branch pipe nozzles; fourthly, marking the forged piece, and heating the forged piece to the temperature of 1180 to 1220 DEG C, determining the dimension of each segment to be forged according to the weight of each segment; fifthly, drawing out the straight pipe segment to the preset dimension of the forged piece; sixthly, drawing out the two branch pipe nozzles, and making sure that the angle formed by the two branch pipe nozzles is 45 DEG. The invention is advantageous in that the branch pipe nozzles configured to form an angle can be accurately forged on the pipe wall of the main pipeline, and the properties of the branch pipe nozzles are stable, thereby the main pipe blank with branch pipe nozzles accords with the design requirements of the AP1000 nuclear power station.