<p>This paper proposes a calculation method of the fatigue life for the cylindrical roller bearing in the spindle unit of machine tool, which takes into account the effects of radial clearance and roller profile, load and misalignment of bearing rings on the fatigue life. Stress distribution is numerically analyzed in elastic half-space for the fatigue life calculation, which is performed using Lundberg-Palmgren model (L-P model). The results of fatigue life calculated by the proposed method are compared with the results of fatigue life by FEM, and the reasonable roller generator is proposed by analyzing the effect of roller generator on fatigue life. A reasonably modified roller generator was applied to the cylindrical roller bearing for spindle of the machine tool, and its effectiveness was verified using the finite element method. The paper analyzed the load characteristics of NN3024 bearing, performs stress and fatigue life analysis under maximum, minimum and average load conditions, and compared the results to verify the improvement of fatigue life.</p>