We propose a hybrid surface plasmonic waveguide structure containing a metal ridge with rounded corners and a special triangular air gap layer. The combination of this particular triangular structure and other materials effectively improves the performance of nano-lasers. We apply the finite element method and use COMSOL Multiphysics software to construct the two-dimensional and three-dimensional models, and use the modal analysis module to analyze the waveguide characteristics of the waveguide structure and the parameters of the laser. The results indicate that the optical field confinement of the designed waveguide can reach a better deep-subwavelength level while maintaining a long propagation length at the 1550 nm operating wavelength. The waveguide structure enables super strong coupling between the surface plasmon polariton mode and the cylindrical mode. The maximum coupling strength is 0.96 and the propagation length is 28047 nm. When this structure is applied to nano-lasers, we adjust the waveguide design parameters to obtain the higher quality factor, lower energy loss, threshold limit, and ultra-small effective mode size. Compared to the previously reported structure with a single triangular air gap, this structure has stronger capacity of field confinement and microcavity bound with the same geometric parameters. So this structure is expected to be applied in the fields of on-chip interconnects, photonic integrated circuits, optical storage, and optical signal process.