Abstract: The characteristics of deformation and failure of coal pillar under goaf water infiltration and overburden load is complex. In order to study the deformation characteristics of coal pillar under the action of lateral permeation-axial load, a unilateral hydraulic loading device for the permeability test of cylindrical specimens was used to carry out compression tests of coal samples under different lateral permeation pressures and to study the failure characteristics and permeability characteristics of coal samples. The results show that: the deformation and failure of coal samples under lateral permeation-axial load can be divided into five stages: compaction, elasticity, stable fracture expansion, unstable fracture expansion and post-peak failure. With the increasing of lateral water pressure, the peak strength of coal samples gradually decreases, and the axial strain corresponding to the stable fracture expansion stage decreases. The water energy enters the inner void of coal sample under small axial strain, resulting in increased brittleness of coal sample and accelerated failure of coal sample.