A secure communication method and a core network node are provided. In the method, a first core network node in a home public land mobile network (HPLMN) receives a first data authentication request sent by a core network node in a visited public land mobile network (VPLMN), and sends a second data authentication request to a home location register (HLR) or a home subscriber server (HSS). The HLR or the HSS generates an end-to-end security key. The first core network node in the HPLMN sends the end-to-end security key to a second core network node in the HPLMN. The second core network node in the HPLMN performs, based on the end-to-end security key, secure communication with a terminal that has roamed to the VPLMN.