In order to overcome the limitations of the Mie scattering method based on approximate theoretical analysis in the study of particle size smaller than the incident light wavelength, this paper used the finite difference time domain (FDTD) method based on numerical simulation to scatter nano-scale. The effect of bulk particles on the near-field focused beam was simulated. The FDTD simulation software was used to simulate the light intensity distribution information around the nano-air particles with the focused linearly polarized light as the light source and the spherical nano-air particles embedded in the beam focus point of the bottom surface of the solid immersion lens. A good focus imaging effect is achieved by changing the corresponding simulation conditions.