Dispersion of multi-clad fiber is solved with equivalent refractive index in this paper. First

the relation between the dispersion of the fiber and the propagation constant and equivalent refractive index is presented. Then

the dispersion of the multi-clad fiber is obtained by solving the propagation constant and the equivalent refractive index of single-clad fiber which is equal to multi-clad fiber. On this basis

the propagation constant is obtained by solving coupled equations with computer iteration

and dispersion of the multi-clad fiber is solved using curve mimesis and differential numerical method. Finally

as an example

the dispersion of triple-clad dispersion-flattened fiber is solved by this method.