Method and device for screwing pre-filled syringe

The invention discloses a method for screwing a pre-filled syringe. The method comprises the steps that a push rod is loaded into a needle cylinder in a conveying station of a conveyor, and the conveyor drives the conveying station to move along a conveying path; pre-screwing the needle cylinder in the conveying station, wherein for pre-screwing, the needle cylinder is rotated by a preset number of turns, and the preset number of turns is set to be smaller than the number of turns required for completely screwing threads of the push rod into a rubber plug of the needle cylinder; and detectingthe relative position of the pre-screwed threads of the push rod and the rubber plug of the needle cylinder, calculating the number of remaining turns of the needle cylinder required to be rotated toreach the target depth, and rotating the needle cylinder according to the calculated number of remaining turns, so that the threads of the push rod reach the target depth in the rubber plug of the needle cylinder, and obtainin