The invention provides a semiconductor structure which comprises a substrate, a semiconductor base, a semiconductor auxiliary base layer, a cavity, a gate stack, a spacer and a source/drain region, wherein the gate stack is arranged on the semiconductor base; the spacer is arranged on a side wall of the gate stack; the source/drain region is embedded into the semiconductor base and is arranged at two sides of the gate stack; the cavity is embedded into the substrate; the semiconductor base is suspended above the cavity; in the length direction of a gate, the thickness of the middle part of the semiconductor base is larger than the thicknesses of the two sides of the semiconductor base; in the width direction of the gate, the semiconductor base is connected with the substrate; the semiconductor auxiliary base layer is arranged on the side wall of the semiconductor base; the semiconductor auxiliary base layer has a doping type opposite to the source/drain region; and the doping concentration of the semiconductor auxiliary base layer is higher than the doping concentration of the semiconductor base. Correspondingly, the invention further provides a manufacturing method of the semiconductor structure. The short channel effect is suppressed, the performance of a device is improved, the cost is reduced, and the process is simplified.