Disclosed is the magnesia integument phosphor powder covered with magnesia on the surface of the phosphor powder.The method of integument comprising: preparing pH buffer with the concentration between 0.1-0.2M by employing conjugate acid and base system with the pH value between 8.0-12.0, weighing relevant quantity of water-soluble magnesium salt according to the proportion between magnesia and phosphor powder by weight (0.25~15): 100, preparing water-soluble magnesium salt volumetric solution with the concentration between 0.01~1M; preparing phosphor powder suspension with the concentration 0.2~5% by adding the phosphor powder into the buffer, stirring, dispersing with supersonic wave to make the phosphor powder dispersed in the buffer; heating the phosphor powder suspension to 20~70 DEG C and keeping the temperature, stirring with speed 100r/m~ 300r/m and dropping the water-soluble magnesium salt volumetric solution into the phosphor powder suspension at the speed of 2~15ml/min, then keeping the temperature and stirring for 30~180 minutes and getting the integument phosphor powder suspension, separating, washing, dewatering and drying at 60-120DEG C, making the integument phosphor powder moisture percentage below 0.25%,incandescing at 200~400 DEG C for 1~3 hours and air cooling in the furnace.