A pre-shared key (PSK) updating method is disclosed. A first communication apparatus stores a first PSK for processing, within an aging periodicity of the first PSK, a packet exchanged between the first communication apparatus and a second communication apparatus. The first communication apparatus may receive, within the aging periodicity of the first PSK, a first protocol packet that is sent by the second communication apparatus and includes a first PSK key material for generating a second PSK. The second PSK is for processing, within an aging periodicity of the second PSK, a packet exchanged between the first communication apparatus and the second communication apparatus.