Abstract: A tube-in-tube structural system is presented, in which the obliquely crossing lattice system composed of concrete filled steel tubes (CFST) is used as the outer tube in ultrahigh-rise buildings, and the detailed CFST intersecting connection is proposed, which satisfies the “stronger connection” criteria. Eight specimens of the connection are tested by a self-equilibrating steel loading equipment with the capacity of 20000kN, to investigate the failure mode, ultimate capacity and collapse procedure. Meanwhile three CFST short column specimens with the same dimension and material are tested in compression to determine the constitutive relation of confined concrete. Based on the test results and the constitutive model of confined concrete, the whole loading response of the specimen is simulated using finite element program, and the effective calculation method for the connection is provided. Observing the inner of the tested specimens, it is found that the failure of the confined concrete depends on its strain.