This study is to investigate the effect of baicalin (BL) against oxidative injury stress of SH-SY5Y cells induced by H2O2 and the possible mechanism. SH-SY5Y cells were pre-incubated with baicalin (25, 50, and 100 micromol x L(-1)) for 12 h prior to exposure to H2O2 (150 micromol x L(-1)) for 24 h. The viability of SH-SY5Y cells was measured by MTT assay. The contents of LDH and NO were determined. The percentage of apoptotic cells was assessed by flow cytometry (FCM). The content of Caspase-3 was tested by immunofluorescence histochemical method. BL at 50 and 100 micromol x L(-1) separately increased the cell viability and up-regulated SIRT1, reduced the contents of LDH, NO, Caspase-3 and the apoptotic percentage of SH-SY5Y cells. This study results suggest that baicalin could inhibit the H2O2-induced neuronal apoptosis. The further mechanism studies show that baicalin inhibit apoptosis via reducing Caspase-3 expression and up-regulating SIRT1.