Abstract: Based on continuous and realtime microseismic monitoring for construction process of diversion tunnels and drain tunnels in a hydropower station， the microseismic information of tunnels excavated by drillandblast method and tunnel boring machine (TBM) were compared and analyzed. The results show that duirng the preparation and germination of immediate rockbursts in deepburied tunnel excavation， the distribution of microseismic events and energy release gradually convert from discrete to relatively concentrative mode in spatial domain， and the number of microseismic events increases obviously. Accumulated released energy of microseismic events and average released energy of plastic volume increase. Energy release of tunnels excavated by TBM is bigger than that by drillandblast method. Before the occurrence of strong rockbursts，there are a lot of mild and moderate rock bursts in the excavation by TBM， which is not found in drillandblast method excavation.

Key words: drillandblast method, tunnel boring machine (TBM), immediate rockburst, microseismic events, rock burst zone