Abstract: The properties of the coupling between two-dimensional dielectric slab and plasma waveguides are investigated with finite difference time domain methods based on the Fullwave module of Rsoft software. The coupling structure was simulated with the software and the coupling efficiency of light transmitting in the dielectric slab and plasma waveguides was calculated automatically the coupling, and then the variation curves of the coupling efficiency with the waveguide dimension and the wavelength of the light were drawn out. It is found that the gap width of MDM waveguide structure is related to the quality of the optical communication, and that the optimal point of the dielectric slab and plasma waveguides are all set at 15 nm according to the variation law of the coupling efficiency obtained by analysis. The coupling efficiency can be increased by 83% after further waveguide optimization of the geometric construction parameters.