In a liquid environment, the instability of the interface layer of the rotating fluid medium is one of the main causes for the failure of magnetic liquid seals. The turbulence intensity of the interfacial layer between the magnetic and the sealing medium fluids in magnetic liquid seals directly affects the layer stability. Reducing the maximum turbulence intensity is an effective way to improve the stability of the magnetic fluid rotating seal. In this study, we simulated magnetic fluid sealing devices with different structures in liquid environments using FLUENT software. The simulation results are verified through experimental analyses and the turbulence intensity at the sealing interface is analyzed. We simulated the magnetic circuit using Maxwell software, and compared the difference between the optimized and traditional structures. The results show that the maximum turbulence intensity of the liquid interface layer increases with the increasing shaft speed. At the same speed, the turbulence intensity is maximized at the shaft interface before gradually decreasing in a multistage linear pattern along the radial direction. The turbulence intensity at the interface of the spindle is relatively large, which seriously affects the stability of the interface. Based on these results, the optimized structure (OS) of the magnetic liquid seal in the liquid environment is designed. The maximum turbulence intensity of the liquid interface layer in the OS is more than 20% lower than that in the traditional structure (TS), and it is independent of the rotation speed. The optimized and the traditional structures have the same magnetic induction intensity distribution at the sealing clearance. The maximum magnetic induction intensity of the OS is 6.25% higher than that of the traditional one. These results provide a reference for designing magnetic liquid sealing devices.