The invention discloses screw pump equipment for exploiting coal bed gas. The equipment comprises a motor, an oil pipe, an oil suction rod and a screw pump, wherein the oil pipe is arranged in an underground sleeve; the screw pump is positioned underground, a stator is arranged on the inner wall of the oil pipe, and the lower end of the oil suction rod is connected with a rotor of the screw pump; the motor is positioned on the ground and can drive the rotor to rotate through the oil suction rod; the oil suction rod is of a hollow structure, an openable plugging structure is arranged at the lower end of the oil suction rod so as to close the annular space of the sleeve and the annular space of a rod pipe, and when the plugging structure is opened, oil is discharged and recovered through the oil suction rod. The screw pump equipment can adopt two discharge and recovery modes to work. The proper discharge and recovery modes are selected according to change of water amount and the two modes can be continuously converted for continuously and stably draining a shaft at a reduced pressure. The equipment changing the discharge and recovery modes does not need power and can drain by virtue of energy of the coal bed gas without the screw pump, so that failures can be avoided. The screw pump equipment can be adaptive to the change of the water amount and can work stably and reliably.