The invention discloses a method for constructing a reinforced concrete combined beam through hybrid inhaul cables. The method includes the steps that firstly, steel beam units are prefabricated, eachsteel beam upper flange is provided with the even number of temporary lifting sheets, meanwhile, inhaul cable devices are correspondingly arranged on a bridge girder erection machine, construction isconducted so that a first steel beam can be erected in position, suspension clasps at the bottoms of the inhaul cables on the bridge girder erection machine are connected with the lifting sheets of the corresponding steel beam upper flange, a mid-span region is in a vertical state, and the end portions are in a cable-stayed state; the inhaul cables are tensioned till the cable force reaches a setvalue, and then the inhaul cables are locked; precast concrete bridge deck slabs are installed; bridge deck slab wet joint concrete is poured; after the bridge deck slab wet joint concrete reaches the designed strength, the inhaul cables and the lifting sheets are disconnected; then a second steel beam is erected, and construction of the two steel beams is finished; and similarly, construction ofa whole bridge is finished. By the adoption of the method, the material use efficiency of a traditional non-support construction reinforced concrete combined beam can be improved, meanwhile, the concrete anti-cracking performance of a hogging moment region of the combined beam can be improved, a series of beneficial effects such as convenient and quick construction are achieved, and the method has wide application prospects in large-middle-span combined beam erection.