Provided is a FinFET device including a substrate having at least one fin, a gate stack, a spacer, a strained layer and a composite etching stop layer. The gate stack is across the at least one fin. The spacer is on a sidewall of the gate stack. The strained layer is in the substrate aside the gate stack. The composite etching stop layer is on the spacer and on the strained layer. Besides, the composite etching stop layer is thicker on the spacer but thinner on the strained layer.