Abstract: Based on the engineering background of the +450 horizontal No. B3+6 fully mechanized top-coal caving face in the approximately vertical coal seam of Wudong coal mine, the spatio-temporal evolution of microseismic events before the occurrence of rockburst was studied aiming at identifing the precursory information of rockburst. The deviation index of microseismic energy and frequency reflecting the degree of energy release anomaly of coal and rock was established. The evolution law of microseismic energy, frequency, deviation index and spatial distribution before rockburst were analyzed. The results show that before the occurrence of rockburst, the daily total energy of microseismicity fluctuates sharply and drops to a low value. The daily event count of microseismicity rises and falls sharply. The deviation index of microseismic energy tends to appear higher, and this value is generally greater than 20. The deviation index of daily event count of microseismicity experiences a peak value, which is greater than 0.8. Microseismic events are spatially concentrated toward the mining face, and the number of microseismic event with high energy increases. The results provide reference for the monitoring and early warning of rockburst in No. B3+6 fully mechanized top-coal caving face and other coal seams with similar mining and geological conditions.