The invention relates to a slide rail assembly. The slide rail assembly comprises a first rail, a second rail, a third rail, a first slide assisting device, a second slide assisting device and a synchronization piece. The second rail can displace flexibly relative to the first rail; the third rail is mounted between the first rail and the second rail; the first slide assisting device is flexibly arranged between the first rail and the third rail and comprises at least a first roll piece and a first mesh feature, the first roll pieces are used for assisting the third rail to displace flexibly relative to the first rail; the second slide assisting device is arranged flexibly between the third rail and the second rail and comprises at least a second roll piece and a second mesh feature, the second roll pieces are used for assisting the second rail to displace flexibly relative to the third rail; the synchronization piece is meshed between the first mesh feature and the second mesh feature.