The invention discloses a manganese-heme coordination polymer nano-particle and a preparation method and application thereof, the nano-particle is formed by manganese ions and two specific carboxyl groups in heme through coordination polymerization, the nano-particle is of a cubic structure, and the average side length is about 20 nm. The preparation method comprises the following steps: in a NaOH solution with the pH value of 7, carrying out hydrothermal synthesis reaction on a manganese source and heme at 120 DEG C for 3 hours; the nano-particle is formed by self-assembly of manganese ions and heme, due to existence of iron and manganese elements, the nano-particle can be used for 1H-MRI imaging of tumors, meanwhile, the nano-particle has excellent photo-thermal conversion performance and can be used for photo-thermal therapy and photo-acoustic imaging of the tumors. Moreover, the nano-particle has nano-enzyme catalytic activity, H2O2 can be efficiently catalyzed through Fenton reaction to generate highly toxic. OH, lipid peroxidation in cells is caused, apoptosis or necrosis of the cells is promoted through a ferroptosis pathway, and then the nano-particles can be applied to CDT and Fe death treatment of tumors.