A method for manufacturing fluorescent powder substrate includes (1) providing a fluorescent powder and glass panels of which one forms a through hole; (2) mixing the fluorescent powder in deionized water solvent to form a slurry; (3) applying the slurry to form a fluorescent powder layer on one glass panel; (4) laying flat a loop of low melting point glass powder on the glass panel on which the fluorescent powder layer is formed; (5) laminating the other glass panel on the glass panel; (6) burning the laminated glass panels at a temperature of 400-550° C. to completely combust organic substance therebetween and to have the low melting point glass powder bonding the glass panels together; (7) evacuating interior between the glass panels through the through hole; and (8) sealing the through hole to form a fluorescent powder substrate.