The present invention provides a bispecific antibody capable of being combined with immune cells to enhance a targeting tumor killing capability, and a preparation method therefor and an application thereof. Antibodies and degradable nanoparticles are connected by using a chemical method, so as to make the one nanoparticle be connected to two or more antibody molecules at the same time, wherein one antibody can be specifically bound with immune cells, and the other antibody or the other antibodies can be specifically bound to tumor cells so as to achieve the effect of enhancing the capability of the immune cells for specifically killing tumor cells in a targeting way.