The invention discloses a roots flowmeter, including a housing. The top of the housing is provided with a cover shell. The inner side of the housing is provided with roots. The top of the roots is provided with a first rotary wheel. The bottom of the roots is provided with a second rotary wheel. The bottom of the second rotary wheel is provided with a rotating block. The bottom of the housing is provided with a bottom frame. The bottom of the inner side surface of the housing is provided with a projection. A sliding block is arranged in the bottom frame. The top of the sliding block is provided with a pressing rod. One side of the sliding block is provided with a sliding screw. The surface of the sliding screw is provided with a nut, and the other side of the sliding block is provided withan extrusion rod. The outer side surface of the housing is provided with a chute. The top of the first rotary wheel is provided with a connecting rod. Through arranging a semi-ring sleeve, a connecting pipe is connected with a through hole, and then two semi-ring sleeves are combined together, and the semi-ring sleeves drive a clamping block to slide on the side of a sliding groove, a screw passthrough a hole, and the connecting pipe is fastened on the surface of the housing, thereby preventing the connecting pipe from separating the hole and improving stability effect of the connecting pipe.