Cinnamyl alcohol dehydrogenase (CAD), which catalyzes the last step of monolignol biosynthesis, is a key enzyme in the biosynthesis of lignin. In this research, the gene SbCAD4 from Sorghum line Early Hegari-sart was amplified by RT–PCR and cloned into pMD18–T. There was only one base difference between the nucleotide sequence of the cloned gene and the SbCAD4 reference gene of Sorghum line IS11861. But the amino acid sequence of cloned gene was consistent with IS11861. Further phylogenetic analysis revealed that gene SbCAD4 belonged to the first group, which contained bona fide CAD genes from Arabidopsis, rice and maize. And it was also identified that SbCAD4 possessed the same motifs with these bona fide CAD genes through the alignment analysis. By verified a constructed recombinant plasmid (pMAL–SbCAD4) and transplanted it into Escherichia coli BL21, we found that the best expression concentration for SbCAD4–fused protein induction with IPTG was 0.5 mmol/L. The electrophoretic analysis showed that there was a single band in the SDS–PAGE gel after purified with affinity chromatography. The catalytic activity of purified protein was at the Km value Kmof 5.2 μmol/L and Vmax value of 5.8 μmol/(min?mg).