The present disclosure provides a manufacturing method of a semiconductor structure and a semiconductor structure. The manufacturing method of a semiconductor structure includes: providing a substrate; forming a plurality of active pillars arranged in an array on the substrate, where the active pillar includes a first segment, a second segment, and a third segment that are connected sequentially, and along a second direction, a cross-sectional area of the second segment is smaller than those of the first segment and the third segment; forming a gate oxide layer on a sidewall of the second segment, a top surface of the first segment, and a bottom surface of the third segment; and forming a gate dielectric layer on the gate oxide layer, where the gate dielectric layer is shorter than the gate oxide layer, and is close to the third segment.