Since we reported that ferromagnetic nanoparticles with intrinsic peroxidase-like activity (Nature Nanotechnology, 2007), nanozyme, as next generation of artificial enzyme, is becoming a rapidly emerging field. Many nanomaterials with different morphologies, sizes and components are found to have intrinsic enzyme-like activities and their catalytic mechanisms are systematically investigated. Because of nanozyme with high efficient activity, stability and low cost at large scale of preparation, it has widely potential applications in biomedicine, chemical industry, food, agriculture and environment. Here we will present our new data that nanozyme applied for tumor diagnosis and therapy.