“…The main purpose of this paper is to search for the full classification of solutions to the high‐order JM equation () by the finite‐gap integration method and Whitham modulation theory 8,14 . The finite‐gap integration method was presented by Flaschka, McLaughlin, and Forest 8 to study the slow modulations of N ‐phase trains for the KdV equation, which permits one to predict wave patterns arising from given initial values, and has been used to study the generalized nonlinear Schrödinger equations with self‐steepening nonlinearity, 45,46 the Camassa–Holm equation with small dispersion, 47 the polarization waves in a two‐component Bose–Einstein condensate, 48 the cmKdV equation, 21,49 the generalized Chen–Lee–Liu equation, 50 and the defocusing AB system 51 with initial discontinuity. Here we extend the method to determine the zero‐genus, one‐genus, and two‐genus solutions of the high‐order JM equation ().…”