A semiconductor device is provided in the disclosure, including a substrate, multiple parallel fins protruding from the substrate and isolated by trenches, and a device insulating layer on the trenches between two fins, wherein the trench is provided with a central first trench and two second trenches at both sides of the first trench, and a depth of the first trench is deeper than a depth of the second trench, and the device insulating layer is provided with a top plane, a first trench and a second trench, and the fins protrude from the top plane, and the bottom surface of the second trench is lower than the bottom surface of the first trench.