A slide rail assembly, comprising: a first rail comprising an abutting feature; a second rail movable relative to the first rail; and an auxiliary member configured to be operated between a first state and a second state relative to one of the first rail and the second rail; a driving device comprising an elastic member, an engaging member and an object, the engaging member being configured to hold the elastic member to accumulate an elastic force, and the object being configured to guide or drive the engaging member; wherein when the auxiliary member is in the first state, a predetermined gap is defined between the auxiliary member and the abutting feature of the first rail to allow the second rail to be moved a predetermined distance from a retracted position relative to the first rail along a first direction, such that the engaging member is guided or driven by the object of the driving device to allow the elastic member to release the elastic force to move the second rail to be opened relative to the first rail along a second direction opposite to the first direction; wherein when the auxiliary member is in the second state, the predetermined gap defined between the auxiliary member and the abutting feature of the first rail is reduced to prevent the second rail from being moved the predetermined distance from the retracted position relative to the first rail along the first direction, such that the engaging member is prevented to be guided or driven by the object of the driving device to allow the elastic member to release the elastic force to move the second rail to be opened relative to the first rail along the second direction. a first rail comprising an abutting feature; a second rail movable relative to the first rail; and an auxiliary member configured to be operated between a first state and a second state relative to one of the first rail and the second rail; a driving device comprising an elastic member, an engaging member and an object, the engaging member being configured to hold the elastic member to accumulate an elastic force, and the object being configured to guide or drive the engaging member; wherein when the auxiliary member is in the first state, a predetermined gap is defined between the auxiliary member and the abutting feature of the first rail to allow the second rail to be moved a predetermined distance from a retracted position relative to the first rail along a first direction, such that the engaging member is guided or driven by the object of the driving device to allow the elastic member to release the elastic force to move the second rail to be opened relative to the first rail along a second direction opposite to the first direction; wherein when the auxiliary member is in the second state, the predetermined gap defined between the auxiliary member and the abutting feature of the first rail is reduced to prevent the second rail from being moved the predetermined distance from the retracted position relative to the first rail along the first direction, such that the engaging member is prevented to be guided or driven by the object of the driving device to allow the elastic member to release the elastic force to move the second rail to be opened relative to the first rail along the second direction.