The application of Surface Plasmon Polariton（SPP）suffers from high loss during propagation and contradiction between subwavelength constraints and propagation distance. The paper proposes an asymmetric dielectric waveguide structure and designsa loaded glass SPP propagate optimization device.The excited model of SPP is similar to Kretschmann structure. It can improve the propagation distance without sacrificing the size of subwavelength waveguide. The Finite Difference Time Domain（FDTD）analysis results show that the improved waveguide structure can significantly increase the SPP propagation distance with higher electric field strength. The SPP propagation distance is increased by more than 20 times. We also compare the performances with different thickness of film layers.The result indicates that the better localization performance can be achieved with thinner film. The proposed structure also significantly increases the SPP coupling effect. The proposed structure has the potential for the application of SPP in the area of new photonic devices

broadband communications systems

small photon loops

and other aspects of integrated optoelectronic applications.