A semiconductor device having integrated MOSFET and Schottky diode includes a substrate having a MOSFET region and a Schottky diode region defined thereon; a plurality of first trenches formed in the MOSFET region; and a plurality of second trenches formed in the Schottky diode region. The first trenches respectively including a first insulating layer formed over the sidewalls and bottom of the first trench and a first conductive layer filling the first trench serve as a trenched gate of the trench MOSFET. The second trenches respectively include a second insulating layer formed over the sidewalls and bottom of the second trench and a second conductive layer filling the second trench. A depth and a width of the second trenches are larger than that of the first trenches; and a thickness of the second insulating layer is larger than that of the first insulating layer.