The M_S7.9 earthquake that struck Myanmar on March 28, 2025, was a major right-lateral strike-slip event on the Sagaing Fault. To address the urgent need for an in-depth understanding of postseismic stress evolution and aftershock-triggering mechanisms, this study employs the Burgers rheological model combined with the PSGRN/PSCMP program to calculate coseismic and postseismic Coulomb stress changes on major faults in and around the source region. The results indicate that the Myanmar earthquake produced significant coseismic and postseismic Coulomb stress loading at both the northern and southern ends of the main rupture zone, with particularly notable triggering effects on aftershocks at the southern end. The mainshock and its aftershocks together filled a nearly 500km-long seismic gap between the 1956 M_S7.0 earthquake and the 1930 M_S7.5 earthquake. In addition, the earthquake imposed coseismic and postseismic Coulomb stress loading on six prominent tectonic structures in the Sichuan-Yunnan region of China, thereby promoting the subsequent rupture of major faults in these areas. In particular, several near-northeast-trending left-lateral strike-slip faults in southern to southwestern Yunnan experienced substantial stress loading, especially the Nanting River fault, where the Coulomb stress increase exceeds the commonly cited 0.01MPa triggering threshold.