The utility model relates to a baffle plate type gas flowmeter. A lifting mechanism tube body as well as a gas inlet tube body and a gas outlet tube body are orthogonal into a whole in the raised shape. A baffle plate replacement opening is arranged at one side of the lifting mechanism tube body. A seal cover, a base, a baffle plate and an O-shaped packing form a baffle plate bracket structure. The baffle plate bracket structure is driven by a lead screw to go up or down along the inner cavity of the lifting mechanism tube body. The baffle plate bracket structure goes up, so that the baffle plate bracket structure is horizontally butted with a tube pillar of the baffle plate replacement opening, so as to be convenient to replace the baffle plate. The baffle plate bracket structure goes down, so that the baffle plate bracket structure is positioned at the linear connection position between a gas inlet tube pillar main body and a gas outlet tube pillar main body, so as to be convenient to exactly measure the volume, pressure and temperature of the gas in a gas-forming pipeline. An assembling opening is mainly convenient for primary assembly and later maintenance of the flowmeter. Under a continuous oil and gas test state, the baffle plate for testing gas is replaced, and the continuous gas test of a single pipeline is realized.