Abstract: The p1 gene of Yersinia ruckeri (yrp1) which was isolated from channel catfish was amplified by PCR with specific primers and inserted into pMD19-T vector. The positive recombinant plasmid was selected and sequenced. Then, the yrp1 gene was subcloned into pET-32a (+) vector and transformed into BL21 (DE3) followed by induction with IPTG and detection with SDS-PAGE. Optimization of the induction conditions were conducted. The results showed that the recombinant protein with a molecular mass of about 72 kDa was mostly packaged into inclusion bodies. The optimization of induction process conditions led us to perform the fusion protein induction at 37°C for 4 h with 0.8 mM IPTG.