The invention discloses a cache management method and device, relates to the technical field of a communication network, and can solve the technical problem of poor cache reliability. The device comprises a master management unit and at least two slave management units. Each slave management unit is used for processing one type of messages. The method comprises the following steps: if the total amount of available caches is smaller than or equal to a first threshold value, the master management unit allocates the available caches to the slave management units respectively according to weight of each slave management unit, capacity of the available cache allocated to each slave management unit being in positive correlation with the weight thereof; or when the cache capacity used by one slave management unit is larger than or equal to a third threshold value, and if the total amount of the available caches is larger than or equal to a second threshold value, the master management unit increases cache capacity of the slave management unit, improves shared cache occupation capability of the slave management unit temporarily and reduces cache capacity of at least one other slave management unit, the increased cache capacity being equal to the reduced cache capacity. The scheme is suitable for shared cache management.