Abstract: Inter-story stiffness identification of shearing structures under ambient excitation was studied and a new method was presented.In the method, the transition from structural random response to deterministic response was realized by the natural excitation technique (NExT).The parameter-decoupled free vibration equation of shearing structures was deduced, and the equation could simplify the process of identification and reduce the amount of calculation.Through the effective combination of the NExT, the parameter-decoupled method and the extended Kalman filter (EKF) algorithm, a good scheme was presented for inter-story stiffness identification of shearing structures under ambient excitation.Using a shearing structure with six-degree-of-freedom as example, the scheme was tested by numerical simulation.The results show that the inter-story stiffness can be identified basically with accuracy, and the scheme can be applied in practical projects for health monitoring of shearing structures.