Disclosed are an interconnected system and an interconnected device for an outdoor activity group that are capable of transmitting RF signals by a public open frequency band and transmitting a data packet in a relay manner without requiring the internet and external communication devices. The data packet includes the positioning information of a machine and each interconnected device, and each member of the outdoor activity group acts as a relay station to unlimitedly extend the communication distance of the whole group in a relay manner, so as to overcome the problem of losing contact caused by a long distance and a failed receipt of signals, and the interconnected system and device can improve the safety of outdoor activities.