Abstract: The coal pillar of roadway protection in deep mine is often in the complex environment of three high and one disturbance, the stability of coal pillar plays a key role in coal mine ventilation, transportation and pedestrians. Aiming at the problem of sudden instability of coal pillar in deep roadway protection under dynamic load disturbance, based on the engineering background of the southern concentrated roadway protection coal pillar in 6302 working face of No.3 coal seam in −980 m level of Xinhe Coal Mine, the failure and instability evolution process of coal pillar in deep roadway protection under dynamic load disturbance is studied based on FLAC^3D simulation software. The influence of dynamic load intensity and coal pillar scale on the dynamic failure evolution of coal pillar is analyzed, and then the dynamic instability cusp catastrophe instability model and discriminant of coal pillar in deep roadway protection are established. The failure characteristics and catastrophe instability mechanism of coal pillar in deep roadway protection under dynamic load are revealed. The results show that:①Increasing the size of coal pillar can improve the stability and reduce the probability of instability failure;②The greater the impact strength of external dynamic load, the overall instability of coal pillar is easy to occur;③Based on the bearing capacity model of coal pillar, the discriminant of coal pillar stability related to external dynamic load strength and coal pillar size is deduced by using cusp catastrophe model and elastic thin plate theory, the discriminant method of instability failure of coal pillar in deep mine under dynamic load disturbance is put forward and verified by engineering. The research results enrich the theoretical system of prevention and control of rock burst caused by coal pillar instability, provide reliable theoretical guidance for the retention and maintenance of coal pillars in the field working face, and provide theoretical basis for the safe and efficient mining of deep working face.