A method for forming a FinFET device structure is provided. The method for forming a FinFET device structure includes forming a fin structure and a fin isolation structure over a substrate, and forming a metal stack over the fin structure and the fin isolation structure. The method for forming a FinFET device structure also includes partially removing the metal stack so that a top surface of the fin isolation structure is exposed, and forming a dielectric material over the metal stack and covering the top surface of the fin isolation structure. The method for forming a FinFET device structure further includes patterning the dielectric material and the metal stack to form a metal gate structure and an insulating structure over the metal gate structure.
展开▼