A slide rail assembly for a server rack, configured to be mounted to a first post and a second post of the server rack, the slide rail assembly comprising: a rail element having a first end part and a second end part; a supporting frame connected to the rail element, the supporting frame comprising a passage; an extension element, a portion of the extension element being arranged inside the passage; a first bracket adjacent to the first end part, the rail element configured to be mounted to the first post through the extension element and the first bracket, the first bracket comprising a side plate, an end plate bent from the side plate and at least one ear part bent from the side plate, wherein the side plate is connected to the extension element, a guiding part is formed on the at least one ear part; a second bracket connected to the rail element and adjacent to the second end part, the rail element configured to be mounted to the second post through the second bracket; characterized by: a hook connected to the first bracket, the hook having at least one blocking part and a blocking wall, wherein the hook is connected to the first bracket through the guiding part by a connection element; and an elastic element configured to apply an elastic force to the hook, and arranged between the first bracket and the hook; wherein the first bracket has a first contact part, the hook has a second contact part, one of the first contact part and the second contact part has an inclined surface; wherein when the first bracket is mounted to the first post, the hook is located at a close position relative to the first post with the blocking part and the blocking wall being located at a first side of the first post and the end plate being located at a second side of the first post opposite to the first side of the first post, in order to prevent the first bracket from moving away from the first post; wherein when the rail element is operatively moved along a first direction to be adjacent to the hook, the rail element is configured to block the blocking wall of the hook to prevent the hook from rotating away from the close position; wherein when the first bracket is operatively moved along a second direction opposite to the first direction with the hook abutting against the first post for dismounting the first bracket from the first post, the first contact part of the first bracket pushes the second contact part, such that the hook is moved away from the close position for being detached from the first post. a rail element having a first end part and a second end part; a supporting frame connected to the rail element, the supporting frame comprising a passage; an extension element, a portion of the extension element being arranged inside the passage; a first bracket adjacent to the first end part, the rail element configured to be mounted to the first post through the extension element and the first bracket, the first bracket comprising a side plate, an end plate bent from the side plate and at least one ear part bent from the side plate, wherein the side plate is connected to the extension element, a guiding part is formed on the at least one ear part; a second bracket connected to the rail element and adjacent to the second end part, the rail element configured to be mounted to the second post through the second bracket; characterized by: a hook connected to the first bracket, the hook having at least one blocking part and a blocking wall, wherein the hook is connected to the first bracket through the guiding part by a connection element; and an elastic element configured to apply an elastic force to the hook, and arranged between the first bracket and the hook; a hook connected to the first bracket, the hook having at least one blocking part and a blocking wall, wherein the hook is connected to the first bracket through the guiding part by a connection element; and an elastic element configured to apply an elastic force to the hook, and arranged between the first bracket and the hook; wherein the first bracket has a first contact part, the hook has a second contact part, one of the first contact part and the second contact part has an inclined surface; wherein when the first bracket is mounted to the first post, the hook is located at a close position relative to the first post with the blocking part and the blocking wall being located at a first side of the first post and the end plate being located at a second side of the first post opposite to the first side of the first post, in order to prevent the first bracket from moving away from the first post; wherein when the rail element is operatively moved along a first direction to be adjacent to the hook, the rail element is configured to block the blocking wall of the hook to prevent the hook from rotating away from the close position; wherein when the first bracket is operatively moved along a second direction opposite to the first direction with the hook abutting against the first post for dismounting the first bracket from the first post, the first contact part of the first bracket pushes the second contact part, such that the hook is moved away from the close position for being detached from the first post.