TIn this paper, Hemiplegic patients have gait characteristics different from normal persons. This paper presents a posture measuring and display system reflecting their characteristics. Patients wear 3 sensor modules on thigh, calf and foot. To enhance measuring precision of each sensor module, 3D accelerometer and 3D gyroscope are combined. Gait posture is displayed in 3D by modeling thigh, calf and foot as connected 3D objects based on data of the sensor modules. For convenience in inspecting unusual gait posture of hemiplegic patients, any view angle of the 3D display can be selected. In addition, the current gait phase of RLA(Rancho Los Amigos) gait cycle is determined and displayed in real-time by utilizing the posture information, The phase sequence and duration of each phase can be used in evaluating gait quality of patients.