Abstract: Three-section type landslide is a common type of rock landslide, and lock segment rock bridge plays a key role in controlling the overall stability of this kind of landslide. Aiming at influence of rock bridge’s angle on failure of lock segment landslide, the locking segment models of 70°, 90°, 110°, 130° different rock bridge angles are constructed. Acoustic emission technique is used to synchronously observe the failure process under uniaxial loading, obtaining the variation law of acoustic emission characteristic parameters during the failure process of the locking section, and a classification criteria of acoustic emission characteristics for different failure modes is proposed based on Gaussian mixture model (GMM). The experimental results show that: ①The failure process of the all lock segment models have obvious stage characteristics, and in the failure process of lock segment models with different rock bridge angles, acoustic emission energy shows a similar changing rule. ②By the classification criteria of acoustic emission characteristics, we can predict the corresponding failure mode, which provides a technical method for stage identification and monitoring of the failure process. ③When the bridge angle is less than 90°, the failure mode of the lock segment model is tension-shear failure while tension fracture dominates. When the angle of rock bridge is 110°, the failure mode is a composite failure of tension-shear while shear effect dominates. When the rock bridge angle is 130°, the splitting failure mode occurs due to compression. ④Rock bridge angle has a controlling effect on the overall strength of the lock segment model, and the bearing capacity of the lock segment model is positively correlated with the rock bridge angle.