The invention provides phosphor based on terpyridine or its derivative. The phosphor is composed of monovalent acid anion and a terpyridine (2,2':6',2''-terpyridine) derivative monovalent tertiary amine cation at the molar ratio of 1:1. The phosphor contains no rare earth element and can be simply synthesized at room temperature. Thus, cost is low. After the phosphor is excited by near-ultraviolet light with wavelength of 200-380 nm, the wavelength of emitted light is within the range of 400-550 nm, and the emitted light is blue light with main peak at 400-425 nm and green light with main peak at 500-550 nm. In addition, the external quantum luminescent efficiency is 40% and above, and the internal quantum luminescent efficiency is 40% and above. Therefore, the phosphor, in cooperation with a proper amount of red phosphor, can be used in the preparation of high-efficiency white LED illuminating devices and has a good application prospect.