The present invention provides a pharmaceutical carrier, which comprises folic acid-conjugated chitosan and a negatively charged polymer wherein said negatively charged polymer and said folic acid-conjugated chitosan complex with each other through electrostatic attraction, and said folic acid-conjugated chitosan and said negatively charged polymer is provided at a suitable weight ratio. Based on the components contained and the weight ratio thereof, the pharmaceutical carrier of the present invention has the advantages of high specificity and good drug-releasing efficiency.