The invention provides a polymer drug carrier and a method for preparing the same. The polymer drug carrier is provided with a core-shell structure, a core comprises polyethylene glycol-distearoyl phosphoethanolamine nano-micelle, and a shell comprises poly-dopamine. The method includes forming the nano-micelle from polyethylene glycol-distearoyl phosphoethanolamine; forming the poly-dopamine shell on the outside of the nano-micelle to obtain the polymer drug carrier. The polymer drug carrier and the method have the advantages that the core and the shell of the polymer drug carrier comprise biodegradable polymers, accordingly, the polymer drug carrier is good in biocompatibility, and few toxic and side effects can be realized; the particle size of the polymer drug carrier is smaller than 50nm, tumor gathering effects and photo-thermal therapy effects can be realized, and tumor cell killing effects can be realized after near-infrared light irradiates on the polymer drug carrier; drugs can be encapsulated by the nano-micelle of the polymer drug carrier, diversified drugs can be loaded under chemical modification effects of the poly-dopamine, and accordingly the polymer drug carrier has an excellent application prospect in the field of medicine and pharmacology.