The invention relates to the field of mechanical equipment for steel pipe deep processing, in particular to a semi-automatic coupling pre-screwing device. The coupling pre-screwing device comprises a base, an elevator is arranged on the base, one end of the elevator is connected with a lifting frame, the lifting frame is connected with a floating frame through a spring, two sides of the floating frame are connected with a force arm, the force arm is connected with two ends of an air cylinder, and a clamping plate is arranged at the upper end of the force arm. The air cylinder is used for acting on the clamping plate on the force arm to fix a coupling on the floating frame, and meanwhile the floating frame is connected with a lifting frame structure connected with the elevator through the spring. The elevator of the structure can push the lifting frame to move up and down to be adapted to couplings with different pipe diameters, and through the spring, the floating frame can move up and down, left and right and front and back to facilitate centering of the couplings and smooth screwing-connection of the couplings and the centers of oil casing pipes. Meanwhile, rolling wheels are installed on the base, so that the whole device can move on a guide rail for steel pipe aligning. The semi-automatic coupling pre-screwing device is simple in structure, low in manufacturing cost, strong in practicability, flexible in operation and easy to operate, shortens production cycles, and improves production efficiency.