Abstract: This paper aims to explore the efficiency and function of pH sensitive polymer micelles for targeted delivery and release of Shiga toxin 1 subunit A to HeLa cells. Recombinantly expressed the Shiga toxin 1 A subunit (Stx1A) and the attenuated variant A subunit (Mu-Stx1A) in Escherichia coli, and used pH-sensitive polymer micelles formed by self-assembly of PEG₈-PDPA₁₀₀-PEG₈ to deliver them to the cervical cancer cells Hela. In vitro activity test showed that the recombinant protein Stx1A could significantly inhibit protein synthesis, but the attenuated mutant Mu-Stx1A could not. Stx1A and Mu-Stx1A were successfully transported into HeLa cells by the polymeric micelles, and the transfection efficiency increased with the protein concentration. After Stx1A micelles entered the cells, it successfully released the active subunit Stx1A, leading to cytopathy and apoptosis, which became more evident with the concentration of Stx1A. Experiments have proved that the polymer micelles can successfully encapsulate, transport and stably release Stx1A molecules into tumor cells, exerting toxic functions to induce programmed cell death. This work indicates that polymer micelles can play an effective role in protein transport, which provides a theoretical basis for the subsequent research and application of Shiga toxin 1 subunit A in tumor therapy.