Defects such as cracks and holes in rocks can easily lead to local damage, which has adverse effects on construction safety and maintenance. The rock mechanics testing system was used to carry out uniaxial compression tests on tuff with double-hole holes of different rock bridge lengths. The acoustic emission （AE）monitoring system was used to monitor the whole process. The AE characteristics of rock deformation and failure process were studied. Based on AE energy, ring count, RA / AF value, b value and other characteristic parameters, the influence of different rock bridge lengths on rock failure was analyzed, and the precursor information of damage evolution characteristics was explored. The results show that the AE parameters change periodically with time, and there are obvious abnormal response characteristics before rock failure. AE energy changes from group earthquake type to solitary earthquake type with the increase of rock bridge length. AE ringing count has experienced quiet period, active period and sudden increase area. AE RA/AF value is sensitive to local small crack propagation. AE b value has experienced rising period, fluctuation period and falling period with time, and the overall trend is decreasing. Each parameter of AE has the precursor of rock failure. The AE cumulative energy, AE cumulative ring count, AE cumulative RA/AF value sudden increase point and the lowest point of AE b value are taken as the “critical failure precursor point” D. The early warning time series follows: AE cumulative RA/AF value > AE cumulative ring count > AE cumulative energy > AE b value.