An inter-cell handover method, comprising: obtaining (S210, S501), by a source cell (600, 900), a key retention policy of a terminal device (120, 800, 1100), wherein the source cell (600, 900) and the terminal device (120, 800, 1100) use a first key to communicate with each other, and the key retention policy of the terminal device (120, 800, 1100) is used to indicate a condition for the terminal device (120, 800, 1100) to determine to retain the first key; determining (S220, S502), by the source cell (600, 900) according to the key retention policy of the terminal device (120, 800, 1100) and a key retention policy of the source cell (600, 900), whether the terminal device (120, 800, 1100) and a target cell (700, 1000) use the first key to communicate with each other, wherein the key retention policy of the source cell (600, 900) is used to indicate a condition for the source cell (600, 900) to determine to retain the first key; and sending (S230, S504), by the source cell (600, 900), a handover request message to the target cell (700, 1000), wherein the handover request message is used to request to hand over the terminal device (120, 800, 1100) from the source cell (600, 900) to the target cell (700, 1000), the handover request message comprises first indication information, and the first indication information is used to indicate whether the terminal device (120, 800, 1100) and the target cell (700, 1000) use the first key to communicate with each other, wherein when the source cell (600, 900) determines that the terminal device (120, 800, 1100) and the target cell (700, 1000) use the first key to communicate with each other, the handover request message further comprises the first key, characterised in that the handover request message further comprises a second key, and a next hop chaining counter, NCC, of the second key, and the second key is a backup key used for communication between the terminal device (120, 800, 1100) and the target cell (700, 1000). obtaining (S210, S501), by a source cell (600, 900), a key retention policy of a terminal device (120, 800, 1100), wherein the source cell (600, 900) and the terminal device (120, 800, 1100) use a first key to communicate with each other, and the key retention policy of the terminal device (120, 800, 1100) is used to indicate a condition for the terminal device (120, 800, 1100) to determine to retain the first key; determining (S220, S502), by the source cell (600, 900) according to the key retention policy of the terminal device (120, 800, 1100) and a key retention policy of the source cell (600, 900), whether the terminal device (120, 800, 1100) and a target cell (700, 1000) use the first key to communicate with each other, wherein the key retention policy of the source cell (600, 900) is used to indicate a condition for the source cell (600, 900) to determine to retain the first key; and sending (S230, S504), by the source cell (600, 900), a handover request message to the target cell (700, 1000), wherein the handover request message is used to request to hand over the terminal device (120, 800, 1100) from the source cell (600, 900) to the target cell (700, 1000), the handover request message comprises first indication information, and the first indication information is used to indicate whether the terminal device (120, 800, 1100) and the target cell (700, 1000) use the first key to communicate with each other, wherein when the source cell (600, 900) determines that the terminal device (120, 800, 1100) and the target cell (700, 1000) use the first key to communicate with each other, the handover request message further comprises the first key, characterised in that the handover request message further comprises a second key, and a next hop chaining counter, NCC, of the second key, and the second key is a backup key used for communication between the terminal device (120, 800, 1100) and the target cell (700, 1000).