The invention discloses an automatic climbing device for a concrete inner cavity formwork. The automatic climbing device comprises an inner formwork bracket located in an inner cavity of an inclined tower column, a plurality of bearing platforms are arranged on the outer side of the inner formwork bracket in a sleeving manner, a climbing device is hinged to each bearing platform, each bearing platform comprises a climbing frame, the two ends of the inner side of each climbing frame are fixedly connected with an upper climbing box and a lower climbing box which are in sliding fit with a climbing rail, and supporting legs supported to the wall face of the inner cavity of the inclined tower column are hinged to the outer side of each climbing frame; and each climbing device includes a climbing oil cylinder, the upper end of each climbing oil cylinder is hinged to the inner side of the corresponding climbing frame, a supporting climbing box is hinged at the lower end of each climbing oil cylinder, and the supporting climbing boxes are in slide fit with the climbing rails. By means of the automatic climbing device, cast concrete segments and the bearing platforms are used for supportingthe inner formwork bracket, alternate pushing and climbing between the climbing devices and the climbing rails are used for driving the bearing platforms and the inner formwork bracket to automatically climb alternatively, the inner formwork bracket can accordingly upwards climb along with continuous upward construction of inner cavity concrete segments, and the construction efficiency is improved.