The invention discloses an optical probe film and a special-purposed organic dye for micro determinations of copper ion contents in water sample. The structural formula of the organic dye provided by the present invention is represented by formula I. On the basis of the organic dye, an active group -COCl is introduced. The -COCl group is subject to an amidation reaction with -NH2 on chitosan, and is fixed on a chitosan film through a covalent bond. With the above processes, an optical probe film is produced. The optical probe film has specific response to copper ions. Because copper ions and organic dye molecules are combined through reversible complexations, when the content of the dissociated copper ions in the water sample is changed, the copper ion content still can be reflected instantly. When in use, the film is immersed in a water sample requiring testing, the film is stood in the water sample for 5 minutes, and analysis and determination can be carried out upon the copper-ion-containing water sample through a spectrophotometer. The optical probe film provided by the present invention has advantages of easy production and low cost. According to the present invention, the optical film does not pollute the water system requiring testing, and can be repeatedly used. With the optical film provided by the present invention, an in situ on-line detection can be realized. (Formula I)