Abstract: Axial-flow gas regulator is an important device to secure the gas delivery of long-distance pipeline. In order to improve the flow field performance of the regulator, its main valve structure is optimized. Solidworks software is used for three-dimensional modeling of the internal flow channel of the main valve before and after improvement. CFX software is also used to visualize the internal flow field. Then, internal pressure, velocity contour and velocity vector of the regulator are obtained. Additionally, comparative analyses is made on the shapes of the valve flow channels and the flow field characteristics of regulator before and after the improvement above and the orifice plate is installed behind the valve. The results show that vortexes in the internal flow channel decrease, local maximum flow rate is significantly lower, pressure distribution is more uniform, the flow field of regulator is optimized and the performance is further improved.