Surface plasmon has a history of more than one hundred years since its birth and has been a brand new discipline-plasmonics. Localized surface plasmon in metal nanostructures can gain very strong near-surface electric field enhancement and has been applied to many types researches successfully. However, there is relatively less study of the interaction between localized surface plasmon and magnetic field in incident light. This paper calculates the near-surface electromagnetic field enhancement of metal nanosphere-nanodisc gap based on the previous achievement. This paper shows that under the excitation of the single tightly radially polarized optical beam, the metal nanodisc can produce localized surface plasmon breathing mode and electric dipole moment mode, which give rise to the longitudinal electric field enhancement at the nanodisc center. And then, because of the resonance interaction of the metal nanodisc and localized surface plasmon electric dipolar moment of the metal nanosphere, a gap mode of localized surface plasmon resonance with efficient longitudinal electric field enhancement can be produced. Through carrying out the numerical simulation, this paper demonstrates that the near-surface longitudinal electric field of metal nanostructure gap mode can obtain 250 times electrical field enhancement relative to the valid transverse electrical field that is used to excite the breathing mode, and the enhancement factor of near-surface magnetic field could be 170. In order to present more clearly the character of the spectrum and the near-surface electromagnetic field distribution of this new metal nanostructure, the near-surface electromagnetic field distribution and the resonant wavelengths of this new metal nanostructure are also studied. The calculation results show that the proposed metal nanosphere-nanodisc nanostructure owns an obvious advantage on the local near-surface electromagnetic field enhancement and a relatively large frequency spectrum. Due to the electromagnetic field enhancement advantage of the metal nanostructure proposed by this paper, the future is not without hope that the results here could be applied to more and more researches, especially biomedicine, and provide a bit of reference in order to fight for novel coronavirus.