The invention discloses erbium-doped yellow green fluorescent powder taking vanadate as a base material. The erbium-doped yellow green fluorescent powder takes phosphate as the base material and a chemical general formula of the erbium-doped yellow green fluorescent powder is KBa1-xVO4:xEr, wherein x is greater than or equal to 0.01 and less than or equal to 0.08; the erbium-doped yellow green fluorescent powder taking the vanadate as the base material is prepared through doping an activated ion Er<3+>; the erbium-doped yellow green fluorescent powder is suitable for near ultraviolet or blue light excitation; an excitation spectrum of the yellow green fluorescent powder is 350nm to 500nm and an emission spectrum of the yellow green fluorescent powder is 500nm to 600nm; the erbium-doped yellow green fluorescent powder can be used for exciting yellow green light under the near ultraviolet or blue light excitation and has stable chemical performance, good luminous performance and good luminous intensity; a preparation method of the erbium-doped yellow green fluorescent powder taking the vanadate as the base material has the advantages that a temperature rising process is simple, the method is simple and feasible, the repeatability is good and a preparation period is short.