Objective To explore the mechanism of Indirubin and tanshinone Ⅱa in promoting the degradation of mutant PML,A216T,RARα by realgar.Methods Different concentrations of realgar were acted on wild type and mutant PML,A216T,-RARα to observe the degradation of PML-RARα in two groups of cells to verify that PML,A216T,-RARα is resistant to arsenic.The concentration of each component was determined according to the IC50 value measured by CCK8,and different concentrations and different combinations of realgar,indirubin,and tanshinone Ⅱa were used to act on the transfected PML,A216T,-RARα cells.Western blotting was used to detect the effects of single use,pairwise combination and triple combination on PML-RARα degradation and autophagy-related factors（ pm TOR,LC3 B）.The proteasome inhibitor carfilzomib and the autophagy inhibitor bafilomycin A1 were used to detect the degradation of PML-RARα in each group of cells by Western blotting.Results Compared with the control group（ without drug intervention）,when the concentration of realgar was 0.5 μmol/L,which was acted on PML-RARα wild type and mutant PML,A216T,-RARα,the expression of PML-RARα were significantly degra ded（ both P ,<, 0.01）.Moreover,the comparison between the groups showed that the expression of PML-RARα of mutant PML,A216T,-RARα was higher than that of wild type（ all P ,<, 0.01）.Compared with the control group,when realgar was 4 μmol/L,indirubin was 8 μmol/L,and tanshinone Ⅱa was 8 μmol/L,and were acted on PML,A216T,-RARα respetively,they could all degrade PML-RARα（ all P ,<, 0.01） and reduce the level of p-mTOR（ all P ,<, 0.01）,increase the level of LC3 B（ P ,<, 0.05 or P ,<, 0.01）.The above effect was the strongest when realgar + tanshinone Ⅱa + indirubin was combined（ P ,<, 0.01）.Compared with the control group,when realgar + tanshinone Ⅱa + indirubin,realgar + tanshinone Ⅱa + indirubin + carfilzomib were used on PML,A216T,RARα,PML-RARα were significantly degraded（ all P ,<, 0.01）.Compared with the control group,carfilzomib alone,bafilomycin A1 alone,realgar + tanshinone Ⅱa + indirubin + bafilomycin A1,when acting on PML,A216T,-RARα,all caused PML-RARα to a significant accumulation,and the expression of PML-RARα in the realgar + tanshinone Ⅱa + indirubin + bafilomycin A1 group was higher than that in the carfilzomib alone and bafilomycin A1 group（ all P ,<, 0.01）.Conclusion The combination of indirubin and tanshinone Ⅱa can enhance the degradation effect of realgar on mutant PML,A216T,-RARα through autophagy,and the combination of the three has the strongest autophagy effect,which may be one of the mechanisms of Chinese medicinal formula Realgar-Indigo naturalis in the treatment of acute promyelocytic leukemia.