The invention provides a method for calculating the diopter of an intraocular lens, in order to solve the problem that the calculation formula of the IOL diopter in the prior art has larger errors. According to the method for calculating the diopter of the intraocular lens, the corneal diopter index is calculated through the anterior corneal surface tangential curvature, the refractive index of ananterior chamber medium is calculated through the anterior corneal surface tangential curvature, and the diopter of the intraocular lens is calculated through the corneal thickness, the anterior chamber depth, the length of optic axis, the intraocular lens parameters, the reserved diopter and refractive indexes of all refractive media of all eyes. The anterior corneal surface tangential curvatureand the posterior corneal surface tangential curvature are introduced into calculation, the position of the effective lens can be accurately predicted through the anterior chamber depth, the lens thickness, the proportions of the inherent morphology of the anterior and posterior capsules of the lens and the A constant of the intraocular lens, system calculation is performed according to the refractive indexes and locations of all refractive media of all eyes, the calculation accuracy of the diopter of the intraocular lens is effectively improved, and the method has statistical difference.