Abstract. Fiber-optic chemical sensor for butylamine was realized. The sensor includes a thin layer nanostructure on the end of optical fiber with a diameter of 600 µm. It consists of luminescent silica nanoparticles modified with pyrylocyanine dye, silver nanoparticles and photonic-crystal film. The sensitivity of the sensor is increased tenfold due to an additional covering of the film with photonic crystal as a porous mirror and the injection of silver nanoparticles with a diameter of 5-7 nm.