The double girder semi-gantry crane with hook is mainly composed of gantry, crane crab, trolley travelling mechanism and electric control system. The gantry, of a box-shape structure, has a leg at its one side and runs along the ground rails, and has no leg at the other side and runs along the rails on the factory workshop. The closed cab is employed for operation, where there are adjustable seat, insulating mat on the floor, toughened glass for the window, fire extinguisher, electric fan and auxiliary equipment such as air conditioner, acoustic alarm and inter-phone which can be furnished as required by users.