The method is applied to a communications system including a first network device, a second network device, and a terminal device. The terminal device is communicatively connected to the first network device and the second network device respectively. The method includes: sending, by a network device, a first message to the terminal device, where the first message is used to determine that the terminal device stops communication with the first network device, or the first message is used to determine that the terminal device releases a protocol stack and a data radio bearer that are corresponding to the first network device; and the network device is the first network device or the second network device. Therefore, power consumption of the terminal device or the first network device and waste of air interface resources can be reduced, and flexibility can effectively be improved in a communication process.