Photonic nanojet (PNJ) has gradually attracted the attention of researchers in the recent years. PNJ has unique properties, such as high intensity, high localization and subwavelength scale focusing ability, making it a narrow beam with wavelength scale. The full-width at half maximum (FWHM) of PNJ at the focus can exceed the diffraction limit while maintaining high intensity with a long distance, which can significantly enhance the imaging resolution. In this work, the characteristics of PNJ are explored through numerical simulation, with a focus on studying the patchy microspheres under various conditions, including coverage area, incident angle, and the refractive index of the immersion medium. The findings reveal that when the microsphere size is fixed and the coverage area accounts for 69%, the performance of PNJ is optimal. Under this condition, adjusting the incident angle to –5.74° can accurately position the PNJ focal point on the microsphere surface. Furthermore, at this specific angle, the patchy microspheres can generated PNJ with “S”-typed and “Y”-typed field intensity distribution, and the FWHM is reduced to 180 nm, significantly exceeding the traditional diffraction limit. This optimization strategy not only facilitates super-resolution focusing, but also greatly enhances both the intensity and efficiency of the PNJ. Additionally, this study demonstrates that the PNJ performance improves when the refractive index ratio between the patchy microsphere and the immersion medium approaches 1.4. Notably, a resonance effect occurs when the refractive index ratio reaches 1.48, resulting in enhanced PNJ performance. In this case, the PNJ focal point remains on the surface of the microsphere, with an FWHM of 180 nm, while the light intensity is further amplified to approximately three times the intensity of the PNJ generated by the microspheres without resonance effect. This research provides theoretical support for the application of patchy microspheres in fields such as super-resolution imaging.