The invention relates to the technical field of production and processing treatment, and particularly discloses a liquid accumulator cover making method applicable to electric resistance welding formation. The method comprises the steps of determining the force application area of stamping, carrying out stamping, guaranteeing the direction of stamping force to form an arch, making the thickness ofa first base be larger than that of a second base, bending the second base to form a cover edge part, then extruding the first base to make the thickness of the first base be equal to that of the second base, forming a boss part on the cover edge, integrating the boss part to make the boss part be annular and placing the boss part at the bottom end of the cover edge part, guaranteeing that the outer diameter of the boss part is equal to the inner diameter of a liquid accumulator shell, and making a welding area be reserved between the cover edge part and the shell. Therefore, it is avoided that the boss part is formed in a cutting manner, it is guaranteed that the thickness of a cover edge is equal to that of a cover body, and that the problems that because uneven stress is prone to happening in the process of using a liquid accumulator, a cover body and a liquid accumulator shell are connected unstably, or the like are effectively avoided.