To explore the anti-tumor proliferation activity of human interleukin-29 (hIL-29) variant and based on bioinformatics analyzed data of hIL-29, a mutant gene hIL-29mut33,35 was amplified by site-directed mutagenesis and megaprimer PCR. The hIL-29mut33,35 was inserted into an eukaryotic expression plasmid pPIC9K and successfully expressed in Pichia pastoris GS115. A recombinant variant protein (rhIL-29mut33,35) was purified from the ferment supernatant of the engineering GS115. To observe the antineoplastic activity of the variant rhIL-29mut33,35, a CCK-8 reagent was used to detect the anti-proliferation effect. Results show that it has strong anti-proliferation effect when acted on liver cancer cell BEL7402, colon cancer cell HCT8 and gastric cancer cell SGC7901. The inhibition ratios of the three tumor cells were (30.99 ± 1.58)%, (22.47 ± 1.37)% and (32.05 ± 2.02)%, respectively. In high dose group, the anti-proliferation effect of the rhIL-29mut33,35 was stronger than that of wild type rhIL-29 (P < 0.01). This indicates the variant rhIL-29mut33,35 has potential development value for medicine.