A slide rail assembly configured to be mounted to a first post and a second post of a rack, the slide rail assembly comprising: a rail member having a first end part and a second end part opposite to the first end part; a supporting rail fixedly connected to the rail member; a first bracket connected to the rail member and adjacent to the first end part of the rail member, the first bracket being configured to be mounted to the first post; and characterized by: a bracket device located adjacent to the second end part of the rail member, the bracket device comprising: a supporting frame movably mounted to the supporting rail and comprising a first engaging feature; a second bracket movably connected to the supporting frame and comprising at least one mounting member configured to be mounted into holes of the second post; a fastening member arranged at one side of the second bracket and configured to lock the second bracket to the second post; and an elastic member having a connecting part movably mounted to the supporting frame, and a first elastic part bent relative to the connecting part to accumulate the elastic force and connected to the fastening member for providing an elastic force to drive the fastening member to deflect relative to the second bracket; an auxiliary elastic member connected between the supporting frame and the elastic member; wherein when the second bracket is located at a second position relative to the supporting frame, the fastening member is in an unlocking state to allow the second bracket to be mounted to the second post; when the second bracket is moved from the second position to a first position relative to the supporting frame, the fastening member is driven to switch from the unlocking state to a locking state by an elastic force of the elastic member, in order to lock the second bracket to the second post. a rail member having a first end part and a second end part opposite to the first end part; a supporting rail fixedly connected to the rail member; a first bracket connected to the rail member and adjacent to the first end part of the rail member, the first bracket being configured to be mounted to the first post; and a bracket device located adjacent to the second end part of the rail member, the bracket device comprising: a supporting frame movably mounted to the supporting rail and comprising a first engaging feature; a second bracket movably connected to the supporting frame and comprising at least one mounting member configured to be mounted into holes of the second post; a fastening member arranged at one side of the second bracket and configured to lock the second bracket to the second post; and an elastic member having a connecting part movably mounted to the supporting frame, and a first elastic part bent relative to the connecting part to accumulate the elastic force and connected to the fastening member for providing an elastic force to drive the fastening member to deflect relative to the second bracket; an auxiliary elastic member connected between the supporting frame and the elastic member; a supporting frame movably mounted to the supporting rail and comprising a first engaging feature; a second bracket movably connected to the supporting frame and comprising at least one mounting member configured to be mounted into holes of the second post; a fastening member arranged at one side of the second bracket and configured to lock the second bracket to the second post; and an elastic member having a connecting part movably mounted to the supporting frame, and a first elastic part bent relative to the connecting part to accumulate the elastic force and connected to the fastening member for providing an elastic force to drive the fastening member to deflect relative to the second bracket; an auxiliary elastic member connected between the supporting frame and the elastic member; wherein when the second bracket is located at a second position relative to the supporting frame, the fastening member is in an unlocking state to allow the second bracket to be mounted to the second post; when the second bracket is moved from the second position to a first position relative to the supporting frame, the fastening member is driven to switch from the unlocking state to a locking state by an elastic force of the elastic member, in order to lock the second bracket to the second post.