Abstract: The impact dynamic load induced by the fracture of thick and hard roof is extremely likely to trigger the impact instability of the surrounding rock in gob-side small coal pillars. Taking the gob-side small coal pillar in 3107 working face of Menkeqing Coal Mine in Ordos, China as the research object, the stress evolution characteristics and deformation laws of the small coal pillar under dynamic load were investigated using field measurement, theoretical analysis and numerical simulation. The influence of dynamic stress waves generated by thick and hard roof fracture on the stability of the small coal pillar was analyzed. The results show that the small coal pillar is subjected to multiple dynamic load disturbances during mining, with the maximum single dynamic load energy reaching 7.51×10⁵ J. Most of the dynamic load acting on the coal pillar originates from the fracture of the lateral roof above it, and the energy released by roof fracturing on the gob-side is more intensive and has higher energy level than that on the main haulage gateway side. The stress level of the small coal pillar fluctuates significantly within approximately 40 m ahead of the working face and is elevated under dynamic load. The closer the dynamic load occurrence is to the coal pillar, the greater the increase in coal pillar stress. Under high-intensity dynamic load, the vertical stress of the small coal pillar increases obviously, with the peak stress rising from 21.80 MPa to 29.00 MPa. The deformation increment of the coal pillar is small before the dynamic stress wave arrives. When the dynamic stress wave propagates through the coal pillar, the deformation at both ends of the pillar increases sharply per unit time. During the loading of the dynamic stress wave, the deformation increment on the gateway side is significantly larger than that on the gob side. Affected by dynamic load, the tensile failure range of the plastic zone on the gateway side of the coal pillar increases slightly. By comparing the micro-seismic events and stress fluctuations recorded by stress meters on the same day, it is found that dynamic load can increase the stress level of the small coal pillar.