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Taking the flow characteristics of special shaped valve port in proportional valve as the research objects, the structural mathematic models of U-shaped, V-shaped and round & divergent shape valve port were established, and also the referencing simulation and experiments were carried out. The flow characteristics were analyzed under the conditions of different pressure drops and different openmouthed sizes of special shaped valve port. The results show that the round & divergent valve port has satisfied control linearity on flow. At the same time, the similar experiment method was adopted, the proportional valve model was designed by using Reynolds similarity criterion with water selected as medium. The flow field visualization experimental study with 2D—PIV testing technology was adopted to analyze the features of special shaped valve port flow field. The results show that the round & divergent valve port possesses good flow characteristics and reduces the area and intensity of vortex which promisingly causes minor flow loss. This study provides design reference for the structure improvement of valve port in proportional valve.