Abstract: The present invention relates to a sequential motion slide assembly, including a middle and inner rail rear locking device, a locking pin and a middle and outer rail rear locking device. During the transition from the first pull-out state to a second pull-out state of the slide, after the locking pin clamped in the middle and inner rail rear locking device makes contact with the middle and outer rail rear locking device, the locking pin slides from the middle and inner rail rear locking device into the middle and outer rail rear locking device along with the movement of the slide and becomes clamped. The embodiments of the present invention increase the stability of sequential pulling of the slide.