The codeinone reductase gene (cor) and the berberine bridge enzyme gene (bbe) were cloned from young leaf of opium poppy(Papaver somniferum L) by RT-PCR and the coding sequences of these gene were analyzed. The result demonstrated that the cloned COR gene sequence was highly homologous to the other COR gene family members showing 98.96% identity to COR1.1. The cloned BBE gene sequence was 94.84% identified with the released BBE genes in GenBank previously. Based on the cDNA sequences of COR and BBE,two fragments about 400～500 bp from each gene with lower identity among them were cloned. The fusion gene BC(744 bp) is fused by the PCR technique. Then the promoter CaMV 35S driven,containing'forward BC fusion fragments-reverse pdk intron-reverse BC fusion fragments',plant siRNA expression vector were constructed based on the vectors pHANNIBAL and pART27. Inhibition efficiency of the expression vector to the morphine synthesis was studied by transforming papaver nudicarule.The work will lay the foundation for breeding a low morphine and high thebaine poppy.