Abstract: OBJECTIVE To observe the protective effects of Tongsaimai decoction preparation on the PC12 cells induced by H₂O₂. METHODS The in-vitro cultured PC12 cells were randomly divided into eight groups such as normal group， hydrogen peroxide group， Tongsaimai decoction with high dose group(5 mg/mL)， Tongsaimai decoction with middle dose group(0.5 mg/mL)，Tongsaimai decoction with low dose group(0.05 mg/mL). After the 200 μmol/L H₂O₂ was added to stimulate the PC12 cells and incubated for 4 h， then the final concentration of drugs (5 mg/mL， 0.5 mg/mL， 0.05 mg/mL) were added and continuously incubated and cultured for 24 h. The MTT assay was facilitated to measure and calculate the cell viability the protection rate of the drugs on PC 12 cells induced by hydrogen peroxide. Finally， the corresponding biochemical indicators like SOD， MDA，NO， LDH and Ca²⁺ were measured. RESULTS The Tongsaimai decoction(5 mg/mL， 0.5 mg/mL， 0.05 mg/mL) possess protective effects on H₂O₂-cellular injury model group induced to PC12 cells injury. The hydrogen peroxide model group revealed that could reduce the SOD activity and SOD inhibition rate(P<0.05~0.01)， conversely could increase the MDA， NO content， LDH activity and Ca²⁺ levels(P<0.05~0.01).Each dose of drugs groups could increase the SOD activity and SOD inhibition rate， conversely could reduce the LDH activity， NO content， MDA and Ca²⁺ levels when compared with the hydrogen peroxide model group showing the significant differences(P<0.05~0.01). CONCLUSION Tongsaimai decoction has revealed the significant protective effects towards the PC12 cells injury， its mechanisms are closely-related to the calcium overload， the oxidative stress and others.