Roots type flow meter

The invention discloses a roots type flow meter. The roots type flow meter is composed of a gas flow and volume correction instrument, a meter head and a measuring room. The gas flow and volume correction instrument is connected with the measuring room through a support; the meter head is connected with the measuring room; the gas flow and volume correction instrument is formed by connecting and sealing a front cover and a back cover, a hinge is arranged between the front cover and the back cover, and the four corners of the front cover and the four corners of the back cover are fixed into a whole through four screws. With a structural connection relation of a shell and a machine core, upper feeding and lower discharging and left feeding and right discharging are both realized, and installing is convenient; through the design of an oil feeding hole, oil is discharged quite conveniently in maintenance; with the independent mechanical design, it is unnecessary to return the whole meter to a factory in maintenan