The invention provides a processing method of black bean whey polypeptide powder with an anti-tumor effect. The method comprises the following steps: adding 3.350 acidic protease into a black bean whey protein concentrated solution for hydrolysis for 20 to 40 minutes, and then adding bromelain for hydrolysis for 10 to 20 minutes; heating hydrolysate obtained at the second to deactivate enzyme, carrying out centrifugation, taking supernate, concentrating the supernate to obtain 15 to 18 percent of coarse proteins, and obtaining black bean concentrated whey polypeptide liquid; adding porous starch into the concentrated whey polypeptide liquid, after the starch absorbs water to realize a balance, adding sodium alginate powder which is 5 to 8 percent of the mass sum of the polypeptide liquid and the porous starch, stewing at room temperature for 1 hour, and then carrying out drying, smashing and screening to obtain the black bean whey polypeptide powder with the anti-tumor effect. Test show that the polypeptide powder can resist digestion of gastrointestinal protease, and the effect of inhibiting tumor cells is not lost. The black bean whey polypeptide powder can be developed as anti-tumor functional food or medicines.