Abstract: The mathematical model of flywheel moment of inertia based on the theory of maximum profit and loss work is derived by theoretical analysis, and the finite element model is established. The stress distribution in different directions is studied by simulation analysis. The results show that the maximum principal stress occurs on a circular surface with a radius of 140 mm, and the flywheel speed is positively correlated with the principal stress. The maximum principal stress first increases along the radius, reaches the peak value and then decreases rapidly with the radius, and is basically constant after the radius is greater than 250 mm The circumferential stress shows a trend of double peaks, and the two peaks are respectively at the transition between the web and the hub and the junction between the rim and the web. The radial stress is a single peak curve, and the radial stress basically decreases first, then increases, and then decreases at different speeds. The research conclusion can provide reference for the structural design of energy storage flywheel.