A method of distributing a security key context, where the method includes receiving, by a mobility management entity, a first indication from a primary base station, where the first indication is used for requesting a path switch from the mobility management entity and indicating that the path switch is triggered by carrier aggregation between base stations, processing the path switch according to the first indication, and keeping, according to the first indication, the security key context for the path switch unchanged, and sending a second indication to the primary base station, to indicate the primary base station to keep the security key context unchanged, or sending a third indication to the primary base station, to indicate the primary base station to acquire a quantity of times of reversal of a next hop chaining counter in the security key context.