Abstract: In order to analyze the flow field and external characteristics, a double-suction large-flow liquid ring pump was simulated to analyze the internal flow field and pulsation characteristics of shell pressure in different axial positions. The results show that the change in the hub diameter mainly affects the distribution of the gas phase, and the gas phase area gradually increases with the decrease of the hub diameter. The curvature of the velocity streamline in the blade passage changes sharply, and the flow velocity near the suction port and exhaust port is high. The secondary flow vortices mainly gather in the compression region and the transition region, and the vortices are more obvious in the transition region of the middle section. The maximum amplitude of pressure pulsation on the inner wall of the shell appears around the circumference angles of 50° and 300°, and the range of pressure pulsation amplitude declines with the decrease of the hub diameter, which is 4.9 kPa, 4.8 kPa, and 4.7 kPa on the three characteristic sections in sequence. The frequency characteristics of different axial locations at the same angle are basically the same. The first-order frequency of the shell pressure pulsation in the compression region is the axial frequency, while that in the other regions is the blade frequency. From the suction region to the exhaust region, the pressure pulsation amplitude corresponding to blade frequency gradually decreases, and increases after reaching the minimum in the compression zone.