The invention discloses a composite nano medicament-loading material for treating cancer and a preparation method thereof. The composite nano medicament-loading material takes UCNPs as a core; a layer of porous material covers the surface of the core; an anti-cancer medicament is loaded in pores; a layer of alkaline manganese compound is deposited on the surface of the porous material; the surface of the alkaline manganese compound is marked with one or more capture molecules or identification molecules. According to the composite nano medicament-loading material for treating cancer and the preparation method thereof, a common antigen antibody identification technology is utilized, and the characteristic that tumour cells can dissolve the alkaline manganese compound is utilized, and the anti-cancer medicament can be released to play a role only after the alkaline manganese compound is dissolved. The alkaline manganese compound in normal cells is hardly dissolved; the anti-cancer medicament is not released or is released slowly, so that the damage to the normal cells caused by the medicament can be greatly reduced; the side effect is low. In addition, an up-conversion luminescence fluorescence imaging technology and a nuclear magnetic resonance technology are combined, so that a double-function imaging mode of a tumour tissue is realized; the identification accuracy rate of the tumour tissue is improved; a treatment effect is observed accurately at any time.