To solve the technical difficulties in the collaborative design of wide range, high accuracy, and smooth ope-ration of domestic reciprocating piston flowmeters, this paper establishes a four piston linkage kinematic model based on crank slider mechanism, and analyzes the piston motion law and dynamic characteristics systematically. By utilizing gap optimization control technology, it studies the influence mechanism of motion pair clearance on piston resistance and lea-kage, breaking through the key technical difficulties of gap matching and dynamic sealing under high-precision working conditions, and ultimately achieves the structural optimization design of a four piston linkage piston flowmeter. Experimental results show that the flow measurement range of the developed prototype can reach 5 ～ 10 000 mL / min, and the error does not exceed ± 0.54% over a 200∶1 turndown ratio. This study can effectively meet the technical requirements of industrial sites for wide range and high-precision flow measurement, and has good engineering applicability.