The invention discloses a sodium nitroprusside-conjugated medicine-carrying prussian blue analogue nano-photothermal therapeutic agent and a preparation method thereof. The particle size of the sodiumnitroprusside-conjugated medicine-carrying prussian blue analogue nano-photothermal therapeutic agent prepared by a hydrothermal reaction method is 205.4nm, and passive targeting can be achieved by means of an enhanced permeability and retention (EPR) effect of a tumor site. Under the illumination of near-infrared laser, the nano-photothermal therapeutic agent can not only induce photothermal ablation of tumor cells through excellent photothermal conversion efficiency, but also can control NO release, thereby improving the EPR effect and increasing intratumoral delivery of nanoparticles. Furthermore, the NO can also inhibit tumor progression by inducing apoptosis of the tumor cells, preventing angiogenesis, reversing multidrug resistance, and the like. On the other hand, due to the structural difference between sodium nitroprusside and potassium ferricyanide, the lattice defects of the nanoparticles are caused, and the drug loading capacity of the nano-photothermal therapeutic agent is accordingly increased. Therefore, after chemotherapeutic drugs are carried, under the irradiation of near-infrared light, the nano-photothermal therapeutic agent can realize dose-controlled NO release and phototherapy and chemotherapy combined oncotherapy. In addition, the sodium nitroprusside-conjugated medicine-carrying prussian blue analogue nano-photothermal therapeutic agent provided by theinvention also has good photothermal stability and certain photoacoustic contrast properties.