It is important to identify the normal range of motion (ROM) of the human joints for both biomechanical and clinical applications. Many diseases and injuries can impair joint mobility, which results in a decline in ROM or changes the gait characteristics. In addition, the decline in ROM is associated with aging as well as an abnormal lifestyle. For health care providers, including physicians and therapists, the restoration of normal ROM is a difficult task. The severity of impaired joint mobility or the postoperative rehabilitation process must be evaluated in comparison with a normal reference value. However, there is no studies have reported the ROM of the Mongolian subjects. In this study, we measured the hip, knee, and ankle joint angles using a multiple wearable inertial sensors. Ten healthy young subjects participated. The sensors were placed on the chest, tummy, thigh, shank, and foot. The 3D motion data were collected during the walking with normal speed and values were analyzed with Matlab software. In our knowledge, it is first to analyze the normal ROM of the Mongolian male subjects. The wearable sensor technology can be applied to both indoor and outdoor environments without any restrictions. The collected data can be reference values for evaluating the disability of the motion and performance in rehabilitation programs.