The invention relates to a switch cabinet assembly fixture and a switch cabinet assembling method. The switch cabinet assembly fixture comprises a base; the base is provided with a supporting structure for supporting a left side plate and a right side plate of the switch cabinet and a left side plate profile and a right side plate profile arranged in a left-right opposite mode for keeping the relative distance between the left side plate and the right side plate; and each side plate profile is provided with a side plate adsorption device for absorbing and fixing the side plate to prevent the side plate from dumping. When the switch cabinet assembly fixture is used, during the switch cabinet frame assembling process, the switch cabinet frame is in a lying state, the height is reduced, the assembling difficulty is reduced, the switch cabinet frame on an overturning platform is changed to be in a vertical standing state from a transverse state after assembling is finished, the labor intensity is reduced, and the production efficiency is improved.