Water sampling device capable of detecting water quality at different depths of river

The invention discloses a water sampling device capable of detecting water quality at different depths of a river. The device comprises a collecting machine body; an impeller groove with an upward opening is formed in the upper side in the collecting machine body; a water inlet device is arranged in the impeller groove; the water inlet device comprises an extension shaft which is in running fit with the rear wall of the impeller groove; the extension shaft is positioned in the impeller groove and is fixedly connected with an impeller; a connecting channel is formed in the lower side of the impeller groove; a sliding groove is communicated with the upper side of the connecting channel, a transmission lead screw is rotatably matched with the wall body between the sliding groove and the impeller groove; an opening block is in threaded connection with the portion, located in the sliding groove, of the transmission lead screw; and a connecting torsional spring is connected between the transmission lead screw and t