The present disclosure relates to the technical field of semiconductors, and provides a semiconductor structure and a manufacturing method thereof. The semiconductor structure includes a substrate, an NMOS transistor, and a PMOS transistor. The NMOS transistor includes a first dielectric layer, a first work function layer, and a first conductive layer that are stacked in sequence. The PMOS transistor includes a second dielectric layer, a second work function layer, and a second conductive layer that are stacked in sequence.