When being in range covered by gateway of blueteeth, mobile station (MS) obtains and stores information of base station of mobile communication network, where MS is located in. when finding out that blueteeth connection to the gateway of blueteeth is disconnected, MS closes down own blueteeth function. In moving procedure, MS compares base station ID obtained currently with base station ID stored; if the compared result is not consistent, then MS keeps off state of blueteeth function; if it is consistent, then MS turns on blueteeth function. The invention also discloses a device for MS to determine time to turn on / off blueteeth function. The invention can prolong stand-by time of MS, reduce unnecessary power consumption, and satisfy requirement of seamless switch between fixed communication network and mobile communication network for MS in FMC service.