On the substrate of modified quartz, two kinds of self assembled ultra thin films were fabricated through layer by layer electrostatic deposition with diazoresin′s sulfonate(DRS) as the polyanion, and chitosan(CS) as the polycation. The self assembly process was monitored by UV Vis spectra and confirmed that the layer by layer deposition takes place regularly. The films obtained both from DRS, CS(CS/DRS film) and from DR, DRS, CS(DR/DRS/CS/DRS film) were photo sensitive. Under irradiation of ultraviolet light, the stability of the films towards polar solvents increases significantly. The kinetic study shows that the rate of the photodecomposition reaction of DR/DRS/CS/DRS films is higher than that of CS/DRS films and doesnt show the first order reaction for both films.