The present disclosure provides a semiconductor structure and a method for preparing the semiconductor structure. The semiconductor structure includes a substrate; a drain disposed in the substrate; a drain contact disposed in the drain; a source disposed in the substrate; a source contact disposed in the source; a gate structure with a bottom disposed in the substrate between the drain and the source; a channel disposed at the bottom of the gate structure connecting the drain and the source; a drain stressor disposed in the drain between the gate structure and the drain contact; a drain strained silicon layer disposed in the substrate surrounding the drain stressor connected to the channel; a source stressor disposed in the source between the source contact and the gate structure; and a source strained silicon layer disposed in the substrate surrounding the source stressor connected to the channel.