The invention discloses a preparation method of a CTX (Cyclophosphamide)-mediated targeting nanocarrier and a nano medicine carrying system. The CTX-mediated targeting nanocarrier system provided by the invention has favorable biocompatibility, slow release property and targeting property. CTX-chitosan derivatives have high targeting selectivity of CTX, so that a nanocarrier is used for recognizing and is combined with MMP (Matrix Metal Proteinase)-2 on the surface of a tumor cell to play a targeting role and simultaneously prevent the generation of a vessel of a tumor tissue; and active substances carried by the carrier can be located and released at a tumor position to kill the tumor cell, and therefore, the carrier system can play double roles of targeting inhibition and tumor cell killing. The preparation method provided by the invention is simple and convenient to operate, stable in process, low in cost, wide applicability for raw materials and wide raw material sources including all chitosan derivatives with hydrophilic substituent groups.