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. PNJ is a narrow beam within the wavelength scale. The Full-width at Half Maximum (FWHM) of PNJ at the focus can go beyond the diffraction limit while maintaining high intensity with a long distance , which could significantly enhance the imaging resolution. This study explores the characteristics of PNJ through numerical simulation methods, focusing on 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 remains constant, the PNJ performs optimally when the coverage area reaches 69%. Under this condition, adjusting the incident angle to -5.74° precisely positions the PNJ focal point on the microsphere surface. Furthermore, at this specific angle, the FWHM is reduced to 180 nm, significantly surpassing the conventional diffraction limit. This optimization strategy not only facilitates super-resolution focusing but also substantially enhances both the intensity and efficiency of the PNJ. Additionally, the study demonstrates that the PNJ performance improves when the refractive index ratio between the microsphere coating 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. Under this condition, the PNJ focal point remains on the microsphere surface, the FWHM remains at 180 nm, while the light intensity is further amplified, reaching approximately three times the intensity of the PNJ generated by microspheres without the resonance effect. This research provides theoretical support for the application of patchy microspheres in fields such as super-resolution imaging.