Abstract: Functionalized diazoresin (DR) through the photochemical grafting reaction between rhodamine B(RhB) and diazonium group (N+2), a novel grafting polymeric dye DRgRhB was obtained. The structure of the grafted polymer DRgRhB was characterized by FTIR, 1HNMR, UVVis and PL spectra. The grafting polymer DRgRhB exhibited excellent thermal stability, and its 5% weight loss temperature (T5%) was over 360 °C. The response of DRgRhB film, which were coated by DRgRhB solution, to pH was monitored by UVVis spectra. In water (pH=7.0),the UVVis absorbance of the film hardly varied with the increase of immersed time. If immerged in hydrazine hydrate aqueous solution (pH=12.0),the absorbance decreased and reached its minimum value, further increased with the immerging time. However, the absorbance of the film continuously rised with the immerging time in acid aqueous solutions, and the response of the film in HCl solution (pH=2.0) was more sensitive than that in acetic acid solution (pH=2.3).