A slide rail assembly, comprising: a first rail arranged with a positioning part and a guiding part; a second rail longitudinally movable relative to the first rail, the second rail being arranged with an engaging feature; a base configured to be located between a first position and a second position relative to the first rail; an elastic member configured to provide an elastic force to the base; and a working member rotatable relative to the base, the working member being arranged with an actuating structure, the actuating structure comprising a first part and a second part; wherein when the second rail is moved relative to the first rail from a retracted position along a first direction, the second rail is configured to drive the working member and the base to move away from the first position through the engaging feature being engaged with the first part of the actuating structure; and when the working member is deflected by the second part of the actuating structure through guiding of the guiding part, the second part of the actuating structure is configured to be engaged with the positioning part to hold the base at the second position, and the first part of the actuating structure is configured to be disengaged from the engaging feature of the second rail; wherein when the base is held at the second position, the elastic member is configured to accumulate an elastic force along a direction toward the first position in order to retract the second rail from a predetermined position to the retracted position along a second direction; wherein the working member is formed with a space, and the first part of the actuating structure is movable relative to the working member through the space, the first part of the actuating structure is arranged with a holding feature for preventing the engaging feature of the second rail from being detached from the working member along a transverse direction, and characterized in that a radial dimension of the holding feature is greater than a radial dimension of the first part. a first rail arranged with a positioning part and a guiding part; a second rail longitudinally movable relative to the first rail, the second rail being arranged with an engaging feature; a base configured to be located between a first position and a second position relative to the first rail; an elastic member configured to provide an elastic force to the base; and a working member rotatable relative to the base, the working member being arranged with an actuating structure, the actuating structure comprising a first part and a second part; wherein when the second rail is moved relative to the first rail from a retracted position along a first direction, the second rail is configured to drive the working member and the base to move away from the first position through the engaging feature being engaged with the first part of the actuating structure; and when the working member is deflected by the second part of the actuating structure through guiding of the guiding part, the second part of the actuating structure is configured to be engaged with the positioning part to hold the base at the second position, and the first part of the actuating structure is configured to be disengaged from the engaging feature of the second rail; wherein when the base is held at the second position, the elastic member is configured to accumulate an elastic force along a direction toward the first position in order to retract the second rail from a predetermined position to the retracted position along a second direction; wherein the working member is formed with a space, and the first part of the actuating structure is movable relative to the working member through the space, the first part of the actuating structure is arranged with a holding feature for preventing the engaging feature of the second rail from being detached from the working member along a transverse direction, and characterized in that a radial dimension of the holding feature is greater than a radial dimension of the first part.