A method, an apparatus, and a system are provided for issuing a partition balancing subtask, which are applied to a controller. After receiving a second partition balancing task, the controller generates a second partition balancing subtask set, where the second partition balancing subtask set includes at least one partition balancing subtask, and each partition balancing subtask records a migration partition, a node to which the migration partition belongs, and a destination node; searches a current partition balancing subtask set, and deletes a repeated partition balancing subtask between the second partition balancing subtask set and the current partition balancing subtask set; and issues remaining partition balancing subtasks after the repeated partition balancing subtask is deleted to the destination node recorded in each partition balancing subtask.