Abstract: OBJECTIVE To investigate the protection mechanism of fusion protein PTD-SOD on SH-SY5Y cell against toxicity induced by sodium dithionite sodium hydrosulfite. METHODS Establish the hypoxia damage model of SH-SY5Y cell induced by Na₂S₂O₄. MTT assay was used to measure the survival of SH-SY5Y cell. LDH, SOD and MDA were measured by spectrophotometric method to analysis the protective effect of PTD-SOD on SH-SY5Y cell and the change of the cell oxidation and antioxidant levels after the hypoxia damage. RESULTS MTT assay demonstrated that PTD-SOD could promote significantly the survival of the cell. LDH release assay and SOD and MDA assay demonstrated that PTD-SOD could promote the levels of antioxidant against the hypoxia damage. CONCLUSION The fusion protein PTD-SOD protects SH-SY5Y cell from death after injury induced by Na₂S₂O₄ and promotes antioxidant ability in cell.