In order to study the dynamic characteristics and fatigue life of the plow bit-holede in the cutting process,according to the coal sample property and structure and motion parameters of plow,the random load of BH38/2 × 400 type coal plow bit was calculated by a software system of coal plow design and calculation. The load was applied to the multi body system model of the coal plow.The dynamic stress and the deformation distribution of the bit-holder in the working process were obtained by dynamic simulation. The fatigue life of the bit-holder was predicted by the rain flow counting of the stress information.Research results show that: under the action of complex mechanics with coal,the load of plow bit is non-linear. Under the action of nonlinear load,the areas with higher dynamic stresses are mainly concentrated in the contact position between rectangular groove of bit-holder and the back of plow bit,and the position of the square screw also suffered higher dynamic stresse. The cumulative fatigue damage of the bit-holder was analyzed by rain flow counting method,and the fatigue life was predicted to be about 475. 7 days. According to the comparison between the test value and the calculated value of plow bit,combined with the practical application feedback of the plow,the accuracy of the simulation results was verified.