The invention provides a methoxypoly(ethylene glycol)-poly(lactide) block copolymer capped with phenylalanine group. The block copolymer is represented by formula (I), wherein R is acyl amine group, a=20-200, b=5-50 and molecular weights of the ethoxypoly(ethylene glycol) block component and the poly(lactide) block component respectively range from 1000-5000 and 1000-10000. The preparation method and use of the block copolymer are also provided.
