The invention relates to a connection structure in power transmission line steel-tube towers and in particular relates to an angle steel opposite joint-type adapter of crossed oblique materials in a power transmission line steel-tube tower, The angle steel opposite joint-type adapter comprises a connected steel tube and a connecting steel tube, wherein the connected steel tube is provided with two gusset plates, and threaded holes are formed on the gusset plates; the connecting steel tube is provided with insert plates and threaded holes are formed on the insert plate; one gusset plate is fixedly connected with two insert plates through angle steel connectors, and the two insert plates are connected at the two ends of the gusset plate respectively; the angle steel connectors are arranged on the upper and the lower parts of an integral body which is defined by the gusset plates and the insert plates; threaded holes are formed on the angle steel connectors; the threaded holes of the angle steel connectors correspond to the threaded holes on the gusset plates and the insert plates and are bolted together for fixation; and the gusset plates that are welded on the side face of the connected steel tube are oppositely jointed with the inserted plates which are welded to the connecting steel tube through four angle lug pieces. Accordingly, the stress performances of connecting joints are improved.