The invention discloses a supporting method for a goaf-side roadway roof. The supporting method comprises the steps that a plurality of continuous asymmetric anchor beam structures are arranged on the goaf-side roadway roof, each asymmetric anchor beam structure comprises a joist device and a plurality of anchor cables fixedly connected to the joist device, a plurality of anchor cable holes are formed in each joist device and used for allowing the corresponding anchor cables to penetrate therein, and the distribution density of the anchor cable holes in the side of a coal pillar is larger than that of the anchor cable holes in the side of integrated coal; during supporting, the number of the anchor cables fixed to the side of the coal pillar of the joist device is larger than that of the anchor cables fixed to the side of the integrated coal of the joist device, and therefore asymmetric supporting of the goaf-side roadway roof is formed. The invention further discloses an anchor beam structure achieving the supporting method. According to the supporting method and the asymmetric anchor beam structure, the problems that strata behaviors of the goaf-side roadway roof are asymmetric and conventional anchor cable composite structures lose efficacy due to horizontal extrusion of connecting components can be effectively solved.