Ammonia has attracted extensive attention, and its popularization and application in various power equipment has become one of the current hotspots. However, in the combustion-based micro power system, the combustion and emission characteristics of ammonia at micro scale are still unclear. In this paper, the combustion and emission characteristics of ammonia/oxygen in micro burner with baffle were studied by numerical simulation. By changing the length, width, position of the baffle and inlet velocity, the effects of various factors on temperature field, NO emission and radiation efficiency were obtained. The results show that compared with micro conventional burner, the addition of baffle reduces the channel temperature, radiation efficiency and NO emission. As the baffle length increases, the channel maximum temperature and NO emission decrease first and then increase. The mass fraction of NO in the exhaust gas increases as the baffle width increases under constant flow rate. As the baffle moves downstream, NO emission presents a parabolic distribution. When the baffle with length of 5 mm and width of 0.5 mm is placed 3 mm away from the inlet, the radiation and emission performance are the best. The mass fraction of NO decreases by 24.71% compared with micro planar combustor.