Full gene sequence of RNA-dependent RNA polymerase (RdRp) from Bombyx mori infectious flacherie virus isolated in Zhejiang Province, China (Zhejiang01/CHN/2002) was cloned. The sequence was 1 920 nucleotides in length coding 639 amino acid residues. Sequences comparison of RdRp showed Zhejiang01/CHN/2002 was 99.7% nucleotide sequence and 99.1% amino acids sequence homology with Japanese strain. The RdRp sequence was aligned with 8 representative picorna(-like) viruses and 8 highly conserved regions were detected. The result indicated their relevance function. Phylogenetic tree of 14 picorna(-like) viruses which RdRp presumed protein sequences revealed that the viruses from Iflavirus genus formed an independent clade. The RdRp was successfully expressed in Bran cells using Bac-to-Bac expression system.