[Objective]To study the role of shikonin in inducing K562 cell apoptosis and its inhibition mechanism.[Methods]Detected shikonin’s anti-proliferative effect on K562 cell with thiazolyl blue staining.Observed morphology of apoptosis with Hoechst 33258 and acridine orange(AO)/ethidium bromide(EB)staining.With reverse transcription-polymerase chain reaction(RT-PCR)to detect apoptosis-related genes:the mRNA(Messenger RNA)expression changes of Bax(B-cell lymphoma gene 2 associated X protein),Bid(BH3 interacting domain death agonist),Bcl-xL(B-cell lymphoma gene xL),PUMAB(p53 up-regulated modulator of apoptosis),Bak(B-cell lymphoma gene2 homologous antagonist),Bcl-w(B-cell lymphoma-w),Bad(B-cell lymphoma gene 2 associated death promoter).Analyzed the changes of intracellular ROS(reactive oxygen species)with DCFHDA(oxalic acid-2’,7’-dichlorofluorescein)staining.Analyzed content changes of intracellular GSH(reduced glutathione hormone)with CMFDA 5-chloromethylfluorescein diacetate staining.[Results]①0.2-1.6 mg/L shikonin had dose-dependent inhibition effect on K562 cell proliferation;②Cells treated with 0.2-0.5 mg/L shikonin had obvious apoptosis characteristics;③In groups treated with 0.2-0.5 mg/L shikonin,the mRNA expression of pro-apoptotic proteins(Bid,Bad,Bak,PUMA,Bax)increased significantly and the mRNA expression of anti-apoptotic proteins(Bcl-w,Bcl-xL)decreased significantly.④In 0.2-0.5mg/L shikonin treatment group,content of intracellular reactive oxygen increased and content of reduced glutathione decreased.[Conclusions]Shikonin had strong inhibition effect on K562 cell proliferation and could induce its apoptosis.The process was accompanied by the changes of intracellular redox state.K562 cell apoptosis induced by shikonin was related with intracellular oxidative stress. [Objective] To study the role of shikonin in inducing K562 cell apoptosis and its inhibition mechanism. [Methods] Detected shikonin’s anti-proliferative effect on K562 cell with thiazolyl blue staining .Observed morphology of apoptosis with Hoechst 33258 and acridine orange (AO) / The reverse transcription-polymerase chain reaction (RT-PCR) to detect apoptosis-related genes: the mRNA (Messenger RNA) expression changes of Bax (B-cell lymphoma gene 2 associated X protein), Bid BH3 interacting domain death agonist, Bcl-xL (B-cell lymphoma gene xL), PUMAB (p53 up-regulated modulator of apoptosis), B-cell lymphoma gene2 homologous antagonist, Bcl- Analyzed the changes of intracellular ROS (reactive oxygen species) with DCFHDA (oxalic acid-2 ’, 7’-dichlorofluorescein) staining. Analyzed content changes of intracellular GSH reduced glutathione hormone with CMFDA 5-chloromethylfluorescein diacetate staining. [Res ults] ①0.2-1.6 mg / L shikonin had dose-dependent inhibition effect on K562 cell proliferation; ②Cells treated with 0.2-0.5 mg / L shikonin had obvious apoptosis characteristics; ③In groups treated with 0.2-0.5 mg / L shikonin, the mRNA expression of pro-apoptotic proteins (Bid, Bad, Bak, PUMA, Bax) increased significantly and the mRNA expression of anti-apoptotic proteins (Bcl-w, Bcl-xL) decreased significantly.④In 0.2-0.5 mg / L shikonin treatment group, content of intracellular reactive oxygen increased and content of reduced glutathione decreased. [Conclusions] Shikonin had strong inhibition effect on K562 cell proliferation and could induce its apoptosis. The process was accompanied by the changes of intracellular redox state. shikonin was related with intracellular oxidative stress.