Sub-wavelength focusing lenses are widely used in optical applications such as optical microscopy, imaging, and lithography. The focused optical field with sub-wavelength structure has additional axial aberrations that severely affect the quality of optical imaging at oblique incidence. A high numerical aperture (0.970) optical metalens design method is presented, which can simultaneously meet the sub-wavelength tight focusing and broadband operation at oblique incidence. Optical field control functions with wide-angle response meta-atoms are used, combined with corrections to the oblique incident optical field by aperture stop. The numerical simulation results show that the metalens with 5μm aperture stop, sub-wavelength tight focusing can be achieved within the incidence angle ±30°, and the peak full-width-at-half-maximum range is 0.600~0.885λ. Sub-wavelength focusing is achieved in the incident wavelength range of 550~750nm with an operational bandwidth of 200 nm.