A slide rail assembly includes a first rail, a second rail, a first locking device and a second locking device. The first rail includes a blocking part. The first locking device is arranged on the second rail and configured to lock the blocking part of the first rail when the second rail is moved to a first predetermined position relative to the first rail, such that the slide rail assembly has a first extension length. The second locking device is arranged on the second rail and configured to lock the blocking part of the first rail when the second rail is moved to a second predetermined position relative to the first rail, such that the slide rail assembly has a second extension length.