The global ocean model, LICOM, developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences, was used to study the influences of both the isopycnal diffusivity and the thickness diffusivity(collectively called eddy diffusion coefficients) in the parameterization of mesoscale tracer transports(GM90 scheme) on the physical fields and CFC-11 distribution characteristics. Two numerical experiments were designed, including a run called CONTROL in which the eddy diffusion coefficients were spatially constant, and the other called BUOYANCY in which the eddy diffusion coefficient(A_ρ) varied in the vertical direction along with the ocean buoyancy frequency below the diabatic layer depth. The simulation results showed that the simulation ability of the physical field was improved to a certain degree in the mixing scheme with the buoyancy frequency-dependent eddy diffusion coefficients. For example, compared to the mixing scheme with constant eddy diffusion coefficients(CONTROL), the Antarctic circumpolar current transport strength in BUOYANCY was increased by about 20%-30%, which was closer to the observations. Relatively strong Antarctic Intermediate Water from CONTROL was reduced in BUOYANCY, resulting in improvement of the simulation of subsurface potential density in the high-latitude region of the Southern Ocean. Nevertheless, a deficiency in BUOYANCY was that the strength of Antarctic Bottom Water was weakened, leading to the potential density in the region of 2000-3000 m depth in BUOYANCY being lower than that in CONTROL. Through analysis of the distribution, storage and transport of CFC-11, it was found that the different values of subgrid parameters had a relatively large influence on the simulation of the CFC-11 in the Southern Ocean. Specifically, compared to CONTROL, more CFC-11 was taken up in the high-latitude region, and transported from the region near the Antarctic continent to the Southern Ocean's main storage area(34°S-60°S), leading to the increase in CFC-11 inventory in the Southern Ocean in BUOYANCY, which was closer to the observations in most areas. In addition, it was found from the analysis of CFC-11 distributions in the given section that a certain improvement of the simulation of potential density in the upper layers of the Southern Ocean in BUOYANCY made the vertical structure of CFC-11 closer to the observation, relative to that in CONTROL.