Bispecific immunotoxins (BITs) are a class of hybrid molecules consisting of the targeting bispecific antibody and the toxic moieties. The portion of bispecific antibody has two distinct targeting ligands and is responsible for the specificity of the immunotoxin. The targeting ligands bind molecular markers highly overexpressed in tumor cells but absent in normal cells. The toxic moieties used are usually derived from plant, bacteria, and fungi, most of them work by inhibiting protein synthesis. Plant toxins commonly used include ricin, gelonin, and pokeweed antiviral protein. And bacterial toxins include Pseudomonas exotoxin (PE) and diphtheria toxin (DT). The toxins in immunotoxins are delivered to the diseased tissue by the specific antibodies and kill the cells. In previous studies, immunotoxins have been proved to be a potential therapeutic tool for tumors. The dual-targeting moieties make bispecific immunotoxins (BITs) have more advantages than monospecific immunotoxins.