The invention discloses a method for synthesizing a long-lasting phosphor material through microwave radiation. The general formula of the long-lasting phosphor material is M(20x0y)MgSi2O7:Eu2+x, Dy3+y, wherein M is one or two of Sr, Ca and Ba, x is larger than or equal to 0.005 and smaller than or equal to 0.05, and y is larger than or equal to 0.05 and smaller than or equal to 0.05. The long-lasting phosphor material adopts silicate as a matrix, europium ions are adopted as an activating agent, arrowhead ions are adopted as an auxiliary activating agent, carbon dust is adopted as a reducing agent, boric acid is adopted as a cosolvent, blue long after-flow is generated, the afterglow time is long, and the brightness is high. The method is simple in preparation technology, short in production period and high in yield. An experiment result shows that the obtained long-lasting phosphor material can be effectively activated by near ultraviolet or visible light source (300-420 nm), blue-green long afterglow of 420-550 nm is generated after activation is performed, and the afterglow persistence can reach up to 10 h or longer when the brightness is larger than 0.32 mcd/m<2>.