The invention relates to a control method for continuous casting of the different steel grade. The method comprises the following steps: firstly, according to the shape and structural parameters of a tundish flow control device, the mixed casting tonnage M is determined, and the value is the molten steel amount correspondingly when the height of the liquid level of the molten steel in a tundish is the height of a retaining dam; according to following formulas, the remaining steel amount of the previous steel grade is determined as Mo (shown in the specification), and when casting of a molten steel large ladle of a previous furnace is finished, speed begins to be slowly reduced; the mixed casting initial tonnage of the tundish is M1, the pull speed is reduced to the lowest pull speed V0 during normal production of the steel grade, and the retaining time is t0; thirdly, according to the casting cross section, the large ladle cast-on tonnage is selected, when the remaining weight of the tundish is M2, the pull speed is reduced to V1 from V0, and large ladle cast-on operation is carried out; fourthly, after large ladle cast-on operation, the amount of molten steel of the tundish is kept M, the pull speed is kept V1, after t2, the pull speed rises to V0, the reference formula of t2 is shown in the specification, the pull speed rises to V0, meanwhile, the molten steel amount of the tundish is kept M, after the retaining time t3 is equal to 5 min to 8 min, the opening degree of a sliding plate of the large ladle is gradually increased, the tonnage of the tundish rises to the normal casting tonnage, and the pull speed rises to the normal production target value.