A method and a storage device for collecting garbage data, where the method includes separately recording a data volume of first data in each segment of a storage device at a current time and a variation of the first data in each segment of the storage device in a preset period of time before the current time; obtaining, by means of calculation, a predicted value of the first data according to the data volume of the first data in each segment and the variation of the first data in each segment; and determining, according to the predicted value of the first data in each segment, a segment whose garbage data needs to be collected. A segment that has more garbage data and whose garbage creating rate is lower is reclaimed preferentially.