The invention discloses a joint section structure for a hybrid beam cable-stayed bridge. The joint section structure comprises a concrete beam-combined beam connecting structure connected between a concrete beam and a combined beam, wherein the combined beam comprises steel girders distributed in the longitudinal direction of the bridge, the steel girders are I-shaped and comprise steel girder top plates, steel girder base plates and steel girder web plates. The steel girder top plates and the steel girder base plates extend into the concrete beam, and the concrete beam-combined beam connecting structure comprises a front pressure bearing plate, a rear pressure bearing plate and a joint section steel web plate. The joint section structure is simple, reasonable in design, high in construction speed and good in using effect, and the problems of complicated structure, poor joint effect and the like existing in a steel-concrete joint portion structure can be solved. The invention further discloses a construction method of the joint section structure. The construction method comprises the steps of 1 erecting a construction support; 2 hoisting a steel structure; 3 constructing the concrete beam-combined beam connecting structure; 4 casting concrete. The construction method is simple in step, reasonable in design, convenient to construct, high in construction speed and good in construction effect.