The present disclosure provides a semiconductor structure of a metal gate and a manufacturing method therefor. The manufacturing method includes providing a semiconductor substrate; uniformly depositing a first hard mask layer on the semiconductor substrate, corresponding to a region where the metal gate is located, patterning and etching the first hard mask layer to form a recess, forming a sloping sidewall on a sidewall of the recess, the sloping sidewall and an upper surface of the substrate forming a groove structure, with the size of an upper part of the groove structure being larger than that of a lower part thereof, and forming a metal gate in the groove structure; and removing the first hard mask layer.