Communication method for reducing delay in an idle or inactive mode and device thereof

A communication method, including, when a terminal device is in an idle mode or an inactive mode, a first control plane functional entity that obtains access network information of the terminal device and sends context information of the terminal device to an access network device corresponding to the access network information. Therefore, when the terminal device is in the idle mode or the inactive mode, the first control plane functional entity obtains the access network information of the terminal device and pre-sends the context information of the terminal device to the access network device corresponding to the access network information. When the terminal device needs to transmit data, the terminal device does not need to wait for the process of transmitting the context information of the terminal device, thereby facilitating reducing a delay.