A slide rail assembly, comprising: a first rail (22, 200) comprising a blocking feature and being formed with a predetermined space; a second rail longitudinally movable relative to the first rail (22, 200); a slide assisting device movably mounted between the first rail (22, 200) and the second rail; an elastic member (58, 202) arranged on the slide assisting device; and a working member arranged on the second rail; wherein during a process of the second rail being moved relative to the first rail (22, 200) along an opening direction, the working member is configured to contact the elastic member (58, 202) in an initial state in order to drive the slide assisting device to move along the opening direction to a predetermined position; characterized in that: when the slide assisting device is located at the predetermined position, the elastic member (58, 202) is configured to release an elastic force through the predetermined space of the first rail (22, 200) to be switched from the initial state to a non-initial state, such that the working member no longer contacts the elastic member (58, 202) in the non-initial state; and when the second rail is further moved relative to the first rail (22, 200) along the opening direction to an extension position, the blocking feature of the first rail (22, 200) is configured to block the working member in order to prevent the second rail from being moved from the extension position along the opening direction. a first rail (22, 200) comprising a blocking feature and being formed with a predetermined space; a second rail longitudinally movable relative to the first rail (22, 200); a slide assisting device movably mounted between the first rail (22, 200) and the second rail; an elastic member (58, 202) arranged on the slide assisting device; and a working member arranged on the second rail; wherein during a process of the second rail being moved relative to the first rail (22, 200) along an opening direction, the working member is configured to contact the elastic member (58, 202) in an initial state in order to drive the slide assisting device to move along the opening direction to a predetermined position; characterized in that: when the slide assisting device is located at the predetermined position, the elastic member (58, 202) is configured to release an elastic force through the predetermined space of the first rail (22, 200) to be switched from the initial state to a non-initial state, such that the working member no longer contacts the elastic member (58, 202) in the non-initial state; and when the second rail is further moved relative to the first rail (22, 200) along the opening direction to an extension position, the blocking feature of the first rail (22, 200) is configured to block the working member in order to prevent the second rail from being moved from the extension position along the opening direction. when the slide assisting device is located at the predetermined position, the elastic member (58, 202) is configured to release an elastic force through the predetermined space of the first rail (22, 200) to be switched from the initial state to a non-initial state, such that the working member no longer contacts the elastic member (58, 202) in the non-initial state; and when the second rail is further moved relative to the first rail (22, 200) along the opening direction to an extension position, the blocking feature of the first rail (22, 200) is configured to block the working member in order to prevent the second rail from being moved from the extension position along the opening direction.