In order to master the spatial distribution of aluminum stress in long-span overhead transmission line, taking JLHA1/G6A-500/280 ultra strong steel cored aluminum alloy conductor as the research object, an aluminum strand Laser grooving and embedded ultra weak fiber grating with high sensitivity and super multiplexing capacity are used to build a stress test platform for aluminum of long-span conductor, The aluminum stress distribution law of long-span overhead transmission conductor under different tension conditions was studied, the finite element model of long-span conductor was established, the stress distribution characteristics of aluminum strand was analyzed, and the correctness of the test results was verified. The results show that when the conductor is under tension, the outer aluminum strand stress is different from that of the sub outer aluminum strand, the stress of the outer aluminum strand is less than that of the sub outer aluminum strand, and the stress of the same layer of the conductor is basically the same; The aluminum strand stress increases linearly with the increase of conductor tension. For every 1% increase of tension, the aluminum strand stress increases by about 10%. Under the action of different conductor tension, the stresses of steel strand and aluminum strand show ring delamination characteristics. The average stress of aluminum strand is less than that of steel strand, and the stress ratio between aluminum and steel strand is about 3:7; The stress distribution of aluminum alloy strand in outer layer and sub outer layer is uneven along the circumferential direction. It is suggested to consider the delamination characteristics of aluminum strand in the linear design of long-span conductor.