Abstract: Novel synthesis and optimal reaction conditions for 4-amino-6-nitroresorcinol hydrochloride（ANR•HCl），a key intermidiate of poly（p-phenylene-2,6-benzobisoxazole）（PBO），were systematically studied. Effect of solvent dosage，activated carbon and FeSO4•7H2O，molar ratio of hydrazine hydrate and reaction time were optimizied with an L18（2×37）orthogonal test and a 2nd step optimization. ANR•HCl was obtained with 90.7% yield and 94.1% purity by selective reduction of 4,6- dinitroresorcinol（DNR）under the optimized conditions of 10.0g of DNR，1.5 g activated carbon，1.0g of FeSO4•7H2O，6.62 g of 85% hydrazine hydrate and reflux for 1 h in 150 mL ethanol. The refined ANR•HCl was identified by FT-IR，1H NMR，13C NMR and MS. The current process has the advantages of excellent product stability，high-selectivity，less organic pollution，easy operation and so on.