Disclosed herein is an immunoconjugate comprising an antibody, a functional motif, and a linker connecting the functional motif to the antibody. According to embodiments of the present disclosure, the antibody may recognize tumor-associated antigens (TAAs), and serves as a targeting module for delivering the functional motif connected therewith to the tumor cells thereby inhibiting tumor growth or detecting the distribution of tumor cells. Also disclosed herein are methods of treating cancers and methods of diagnosing cancers by use of the present immunoconjugate.