The invention belongs to the technical field of a steel structure, and particularly relates to a steel tie rod assembly and a steel tie rod tensioning construction method. The steel tie rod tensioning assembly can be tested through being installed on two support tables, and comprises a steel tie rod, wherein one end of the steel tie rod passes through one support table to be tightly fixed; the other end of the steel tie rod is connected with a force measuring sensor fixed on the other support table through the pin shaft end of the steel tie rod; one end of the steel tie rod passing through one support table is fastened on the corresponding support table through a screw nut; the screw nut is connected with a torque sensor through a sleeve; the tail end of the torque sensor is connected with a torque spanner; and a plurality of screw nut pin holes are distributed in the circumferential surface of the screw nut. The steel tie rod assembly and the steel tie rod tensioning construction method have the advantages that the tensioning construction is convenient and fast; the construction cost is reduced; the tensioning process controllability is good; the construction precision is high; and safety and reliability are high.