Based on the electro-magnetic radiation theory and the optical vector field integral theory, the relation between the property of optical vector focal fields and the numerical aperture has been studied. The electric and magnetic dipoles arrays are located along the optical axis in the focal volume. The radiation fields of them are collected and focused reversely. By manipulating and optimizing the dipole parameters and reversing the focused optical field with different numerical apertures, we study the rule of the optical needle and diffraction limited three-dimensional optical tube changing with the numerical aperture. The results show that the longitudinal polarization component purity, the edge slope and optical needle length decline with the decrease of numerical aperture and the full-width at half-maximum increases. The optical tube field is still azimuthally polarized with an intensity null at the center. The length of the intensity null along radial direction will increase. The research has significance on the application of focused vector beam under different numerical apertures.