The invention relates to an offset frequency characteristic simulating calculation method for a two-level main spring non-equal offset frequency gradually changing stiffness plate spring suspension, and belongs to the technical field of suspension steel plate springs. The offset frequency characteristic of the two-level main spring non-equal offset frequency gradually changing stiffness plate spring suspension can be calculated in a simulating manner according to structural parameters of first-level main springs, second-level main springs and auxiliary springs, elastic modulus, U-bolt clamping distances and initial tangent arc heights, idle load and rated load based on contact load and gradually changing clamping stiffness simulating calculation. According to vehicle driving smoothness test of a model machine, the offset frequency characteristic simulating calculation method for the two-level main spring non-equal offset frequency gradually changing stiffness plate spring suspension is correct, and a reliable technical method is provided for suspension offset frequency characteristic simulating calculation. By the method, reliable suspension offset frequency simulating calculation values under different loads can be acquired, product design level, performances and vehicle driving smoothness can be improved, design and experimental expenses are reduced, and product development is accelerated.