The invention relates to the technical field of medical instruments, and discloses a semi-automatic surgical instrument pretreatment machine. The semi-automatic surgical instrument pretreatment machine comprises a treatment box, a control panel, a power line, a cover, supporting legs, a waste liquid box, wheels, a groove, a gap, a notch, a soaking tanks, voids, communicating pipes, a first pistoncylinder, a second piston cylinder, a third piston cylinder, first pistons, a second piston, first pressing rods, second pressing rods, a transverse rod, third pressing rods, a foot pressing plate, acheck block, connecting rods, fixing rods, a soaking basket, an instrument basket, arc-shaped hooks, leaking holes, a containing area, a cleaning agent containing box, a humectant containing box, telescopic motors, telescopic rods, first rotating motors, supporting blocks, first threaded rods, moving blocks, lifting rods, directional rods, first sliding grooves, a waste liquid pipe, a second electromagnetic valve, a liquid discharging pipe and a third electromagnetic valve. The soaking time can be effectively and accurately controlled, surgical instruments can be prevented from being corrodeddue to long-time soaking of the surgical instruments, meanwhile, use of a humectant can be reduced, the cost is effectively reduced, and the time and the cost are saved.