An amphiphilic star block copolymer of poly(L-lactic acid)-b-poly(ethylene glycol) (PLLA-b-PEG) was synthesized using a hexachlorocyclotriphosphazene ring (N3P3Cl6) as a core. N3P3(OC6H4-p-CHO)6 was prepared by the reaction between the hexachlorocyclotriphosphazene core and 4-hydroxybenzaldehyde sodium salt. N3P3(OC6H4-p-CH2OH)6 was then obtained by reduction of N3P3(OC6H4-p-CHO)6. N3P3(OC6H4-p-CH2OH)6 was used as an initiator to obtain a PLLA-grafted star branched polymer by polymerizing lactide, which was then treated with succinic acid to produce a carboxylated PLLA-grafted star polymer. PEG blocks were attached to a carboxylated PLLA-grafted star polymer to produce an amphiphilic PLLA-b-PEG-grafted star block polymer by additional esterification with poly(ethylene glycol methyl ether).