Abstract: A method of making phosphorescent fiber having phosphorescent particles composed, by weight, of 55-62.5% of strontium oxide, 35-42.5% of aluminum oxide, 1-9% of dysprosium oxide and 0.5-1.5% of europium oxide encapsulated with a wall material. The encapsulated particles are mixed and pelletized at a weight ratio of 15-25:85-75 with polymer capable of fiber formation to give a master batch, which is then compounded at a weight ratio of 30-70:70-30 with a polymer mixture, in combination with a softener and a dispersing agent. Polymer mixture consists of two polymers. One is the same polymer used to produce a master batch, the other is a polymer in the same chemical structure but different in physical properties such as melt index and tenacity. The compounded chip is melt-spun at 190-290° C. through a melt extruder. The fibers with the encapsulated phosphorescent particles exhibit such excellent physical properties as to be applicable to various textile products and show a high degree of luminescence.