In the process of using LED as lighting source, the optical field is the key factor in LED applications and is regulated by secondary optical system, which is complex in design, large in size and heavy in weight. With the development of miniaturization of LED optical encapsulation system, the application of secondary optical system will become more difficult. Combined with software simulation and experimental verification, the optical field regulation function of primary optical lens for the monolithically integrated light-emitting diode (MI-LED) was explored. The research results show that the optical field of experimental LED light sources is almost consistent with that of simulated LED light sources, and the designed primary lens can adjust the beam angle of LED light source from 120° to the range of 48°～72°. Compared with the LED light source without primary lens, the LED light source with primary lens has higher light extraction efficiency (LEE) and more uniform spatial light color distribution.