An etching method adapted to forming grooves in Si-substrate and FinFET transistor manufactured thereof are provided. The etching method includes providing a silicon substrate, at least two gate structures formed on the silicon substrate and at least two gate spacer structures disposed on the silicon substrate; performing a first etching process on the silicon substrate to form a first groove, which has a base and two inclined sidewalls, ascending to respective bottoms of the gate structures, and are interconnected with the base, respectively; and performing a second etching process on the silicon substrate at the base of the first groove, so as to form a second groove in an inverted -symbol shape, wherein the two inclined sidewalls of the first groove are interconnected with the second groove respectively, and the first etching process is substantially different from the second etching process.