The present application discloses a method and apparatus for allocating an availability zone. A specific implementation of the method includes: receiving an availability zone allocating request sent from a user terminal, the availability zone allocating request including a user identification and a target logical availability zone identification; matching the user identification and the target logical availability zone identification in an availability zone allocation table; acquiring weights of availability zones from a preset availability zone weight table, selecting a target availability zone from the availability zones by using a ratio of the weights of the availability zones to a sum of the weights of the availability zones as a selection probability, and allocating the target availability zone to the user terminal, in response to an unsuccessful matching of the user identification and the target logical availability zone identification in the availability zone allocation table.