In this paper, a novel hybrid plasmonic waveguide with a metal ridge and a dielectric layer of low refractive index was demonstrated. We numerically simulated the waveguide by using finite-element method. The COMSOL Multiphysics Software is a superior numerical simulation software to simulate the real physical phenomena based on finite element method. On the basic of the COMSOL Multiphysics Software, a three-dimensional model was built. Using the modal analysis module and the frequency domain analysis module, we analyzed the normalized mode scaling factor, distance, lasing threshold and quality factor. The results indicated that the waveguide structure can reach good deep-subwavelength mode confinement while maintaining long distance at the 370 nm working wavelength. Compared to the previously reported structure with a metal plate, it has better waveguide performance. When this structure applied to nanolasers, the electric field distribution in nanolasers is stable and concentrated on a tiny area. In the case of good waveguide characteristic, the nanolasers can keep low gain threshold and high quality factor of the resonant cavity at the 370 nm working wavelength. By comprehensive consideration, the optimal size can be choosed as ｒ＝80 nm, d＝45 nm. In this case, the effective mode area was , the distance was 1 668 nm, the lasing threshold was 1.68, and the quality factor was 74.5. Finally, the emission spectrum was obtained by simulation at the optimal size. The emission wavelength was 360 nm, and the output power was increased 3 100 times than the input power. This structure affords technical support to miniaturization and integration of lasers which have broad application prospects in the field of the biomedical and optical communications.