The invention provides a carbon nanotube/phthalocyanine/polyaniline three-element composite material, and a preparation method and application thereof, and relates to a three-element composite material, and a preparation method and application thereof. The invention aims to solve the technical problem that polyaniline can not be uniformly distributed on the surface of a carbon nanotube easily in the existing method. The three-element composite material provided by the invention is prepared from a nanotube, tetra-beta-carboxyl metal phthalocyanine, aniline, ammonium persulfate, N,N-dimethylformamide and distilled water. The method provided by the invention comprises the following steps: 1, equally dividing the distilled water into two equal parts, and adding the ammonium persulfate into one part of distilled water to prepare an ammonium persulfate solution; 2, sequentially adding the tetra-beta-carboxyl metal phthalocyanine and the carbon nanotube into the DMF (N,N-dimethylformamide), performing ultrasonic vibration, performing centrifugal separation, washing with water, drying, sequentially adding the aniline and the remaining distilled water, performing further ultrasonic vibration, and slowing adding the ammonium persulfate solution; and 3, performing stirring reaction, filtering, sequentially washing with distilled water and anhydrous ethanol, and drying. The product provided by the invention can be used in the field of chemical sensors.