High performance heat resistant polyimide film possesses high glass transition temperature, excellent mechanical property, chemical resistance, heat resistance and low thermal expansion However the polyimide after imidized from polyamic acid has a difficulty in deformation and poor adhesivity. The cyclized imide ring can be opened by ammonia at 3$0^{circ}C$, and amide and amino groups can be produced. The ammonia treated polyimide may have better deformability and adhesivity. The imide ring opening by the ammonia treatment and the imide ring formation by second thermal imidization were confirmed by FT-IR and contact angle measurement. Tensile property and thermal stability were decreased with proceeding of the imide ring opening.