A mobile terminal device detects current communication environment status of the device and calculates a value of a radio quality index (RQI), and adjusts the roaming threshold according to the value of the RQI. The device further calculates a value of a user movement index (UMI) and adjusts the frequency of the device for scanning object access points. After determining the object access point that has satisfied a roaming threshold, the device ends the communication between the device and the current access point, and establishes a communication between the device and the object access point.