The invention provides an ultrasonic guided wave frequency dispersion curve calculation method, and belongs to the technical field of ultrasonic measurement. As the thickness of a to-be-tested plate structure is increased and the structural complexity is increased, when a finite element model of the to-be-tested plate structure is constructed, if a traditional finite element analysis method is adopted, a high-order polynomial interpolation function needs to be adopted, and a large number of units need to be divided, so that the number of finite element grids is increased, and the calculation efficiency is reduced. According to the method, the shape function of the interval B-spline wavelet unit is adopted as the interpolation function for solving, the calculation precision can be guaranteed, a large number of units do not need to be divided, the number of finite element grids is reduced, and the calculation efficiency can be improved.