Labyrinth regulating valve plays an important role in reducing or avoiding the adverse effects of cavitation, flash, vibration and noise in the bypass system through the unique labyrinth disc structure. However, the disc structure will also lead to complex flow field changes in the valve and increase the flow loss. The working principle of the labyrinth regulating valve was introduced, the simulation model of the regulating valve was established, and the accuracy of the simulation model was verified through the flow coefficient and mass flow rate. Aerodynamic characteristics under different valve opening degrees were analyzed and the losses at different opening degrees were studied quantitatively by using the entropy production rate and the volume fraction of entropy production rate. The results show that the velocity in the valve decreases with the decrease of the opening, but the pressure does not change linearly; the low frequency velocity fluctuation in the valve may be an important reason for the noise and fluid-induced vibration in the valve; the high loss area mainly concentrates in the flow area of labyrinth disc, and the loss increases regularly with the increase of opening.