Abstract: With the use of grained granite as samples，the acoustic emission technique was used to investigate AE characteristics in failure process of granite rock samples under biaxial loading condition by applying different lateral stress，and emphasized the relationship of compressive strength，acoustic emission activity and lateral pressure. The results showed that the lateral stress increases the vertical compressive strength. The critical lateral strain at the loading end is the key factor that the later stress affects the vertical compressive strength. When the critical lateral strain at the loading end turns positive that sample experiences tension in the direction，the lateral stress plays a positive role in the increase of vertical compressive strength，otherwise is negative. Also，the lateral stress impacts on the acoustic emission sequence obviously. When the lateral stress is low，few acoustic emission events occur during the initiation of rocks loading. But as a large amount of acoustic emission events occur near failure，the acoustic emission sequence before stress peak shows up as the unimodal type. When the lateral stress is high，even a small stress disturbance may induce the generation and expansion of cracks that results in the acoustic emission sequence showing up as the cluster type，that have a great significance to forecast the rock failure.

Key words: Acoustic emission(AE), Biaxial loading, Lateral stress, AE sequence characteristics