Abstract: The construction technology for the bidirectional asymmetric large cantilevered steel truss of a gymnasium was discussed. The difficulties during the construction were analyzed, including the large span, the large height, the strict requirement and the tight schedule. Through analyzing the difficulties, the design of support system, steel truss lifting, stress and deformation monitoring were highlighted. The modular lattice steel columns and hot-rolled H-beams were used in the support system; the reasonable ceiling order was developed to ensure the safety and stability; the manual screw jack was used during uninstalling, obeying the  principles that the procedure should be done by steps and multiple cycles and declined little by little; the deformation monitoring was done during the whole construction to ensure the safety and reliability. The feasibility of the construction techniques used in similar structures was concluded from the analysis of the construction technology