The invention discloses a steel tube clamping device. The steel tube clamping device comprises a supporting base, a screw rod is arranged on the supporting base, the screw rod is arranged in a threaded hole which is located at the lower end of a sleeve rod, a blind hole is formed in the upper end of the sleeve rod, a spring is arranged in the blind hole, a mandril is arranged in the blind hole, and the upper end of mandril is arranged in a groove of a top plate; a supporting plate is arranged above the top plate, a slide rail is arranged above the supporting plate, a sliding column A and a sliding column B are slidably arranged on the slide rail, one side of the sliding column A is provided with a fixed column A, one side of the fixed column A is provided with a clamping device A, one side of the sliding column B is provided with a fixed column B, one side of the fixed column B is provided with a clamping device B, the other side of the sliding column A is provided with an actuator A, the actuator A is arranged on a support body A, the support body A is arranged above the supporting plate, the other side of the sliding column B is provided with an actuator B, an actuator B is arranged on a support body B, and the support body B is arranged above the supporting plate.