The present invention provides a functional material, its preparation method, and an organic light emitting diode display panel, which belongs to the display technical field and can solve the pollution problem in current organic light emitting diode display panels. The functional material comprises an inorganic mixed powder with a modified layer, the inorganic mixed powder comprising boron oxide, sodium oxide, lithium oxide, zirconium oxide, aluminum oxide, zinc oxide, titanium oxide, silicon dioxide, calcium oxide, silver complexes, silver phosphate, silver nitrate, tourmaline, silver thiosulfate, carbon nanotubes, aluminum sulfate, manganese, manganese oxide, iron, iron oxide, cobalt, cobalt oxide, nickel, nickel oxide, chromium, chromium oxide, copper, copper oxide, magnesium oxide, boron carbide, silicon carbide, titanium carbide, zirconium carbide, tantalum carbide, molybdenum carbide, boron nitride, chromium nitride, titanium nitride, zirconium nitride, aluminum nitride, chromium boride, Cr3B4, titanium boride, zirconium boride, tungsten disilicide, titanium disilicide and the like; the modified layer being generated by a reaction of a dianhydride and a diamine.