An information backup method, wherein the method is applied to a communications system, the communications system comprises a primary device, a secondary device, and a cloud device, and the method comprises: sending, by the primary device, a first identity notification to the cloud device, wherein the first identity notification is a notification indicating that the primary device has a primary device identity; determining, by the primary device, a communication status of the cloud device; and uploading, by the primary device, obtained first user information to the cloud device when determining that the communication status of the cloud device is normal, wherein the first user information is stored by the cloud device and provided to the secondary device, and the first user information is to-be-backed-up information of user equipment that gets online from the primary device when the communication status of the cloud device is normal, wherein the method further comprises: when the primary device determines that the communication status of the cloud device is abnormal and that the primary device and the secondary device can normally communicate with each other, sending (S703a), by the primary device, obtained second user information to the secondary device for backup, wherein the second user information is to-be-backed-up information of user equipment that gets online from the primary device when the communication status of the cloud device is abnormal. sending, by the primary device, a first identity notification to the cloud device, wherein the first identity notification is a notification indicating that the primary device has a primary device identity; determining, by the primary device, a communication status of the cloud device; and uploading, by the primary device, obtained first user information to the cloud device when determining that the communication status of the cloud device is normal, wherein the first user information is stored by the cloud device and provided to the secondary device, and the first user information is to-be-backed-up information of user equipment that gets online from the primary device when the communication status of the cloud device is normal, wherein the method further comprises: when the primary device determines that the communication status of the cloud device is abnormal and that the primary device and the secondary device can normally communicate with each other, sending (S703a), by the primary device, obtained second user information to the secondary device for backup, wherein the second user information is to-be-backed-up information of user equipment that gets online from the primary device when the communication status of the cloud device is abnormal. when the primary device determines that the communication status of the cloud device is abnormal and that the primary device and the secondary device can normally communicate with each other, sending (S703a), by the primary device, obtained second user information to the secondary device for backup, wherein the second user information is to-be-backed-up information of user equipment that gets online from the primary device when the communication status of the cloud device is abnormal.