Mountain climbing is one of the main leisure activities for modern people. Mountaineering accidents include altitude sickness, missing, and accidental falling over cliff. This paper proposes a mountaineering-assisted wearable device and emergency rescue system architecture which comprises a wearable device, a piece of mobile device application software, and a backend management platform. The wearable device has a heartbeat monitor which reminds mountaineers of the signs of altitude sickness and an inertia sensor which notifies falling. Additionally, the device is equipped with Bluetooth and thus can be connected with mobile devices. An application on mobile device can transmit the geographical information and the information in the wearable device to the backend management system through mobile devices. This systematic architecture can effectively prevent mountaineering accidents, guide mountaineers, and inform relevant units so that they can offer emergency rescue as soon as possible.