The embodiment of the present application provides a key generation method, which relates to a terminal device, a network device and a computer-readable storage medium, wherein the method includes: determining a first key based on the long-term key; generating the session key based on the first key and at least one additional key, communicating with the network side based on the session key; wherein, the at least one additional key includes: an initial session key generated when the terminal device is connected to the network for the first time, and/or a session key used in the last communication; the first key and the at least one additional key are both symmetric keys.