The invention relates to a design method of the free tangent camber height of dual reinforced root unequal-thickness tapered leaf springs and belongs to the technical field of suspension less-leaf tapered leaf springs. According to the design method, the free tangent camber height of the dual reinforced root unequal-thickness tapered leaf springs can be designed according to the number of the leafsprings, structure parameters of the leaf springs, elasticity modulus, the thicknesses of root pads and end pads, the initial tangent camber height of the first assembled and clamped leaf spring, andthe design required value of pre-clamping stress of the leaf springs. Prototype testing shows that the design method of the free tangent camber height of the dual reinforced root unequal-thickness tapered leaf springs is correct and can obtain the accurate and reliable design value of the free tangent camber height of the leaf springs. By means of the method, the initial tangent camber height ofthe first leaf spring and the pre-clamping stress of the leaf springs can meet the design requirement, the design level and reliability of products and vehicle running safety can be improved, meanwhile, the design and testing cost of the products is reduced, and the product development speed is increased.