Based on the bioinformatics and comparative genomics methods,the COBRA gene family of Sorghum bicolor was identified,and gene structure,phylogenetic relationship,selection pressure and expression patterns were analyzed,so as to lay the foundation for further study of the function of the COBRA gene.The results showed that 10 COBRA genes were identified from the genome of Sorghum bicolor,named SbBC1 and SbBC1L1—SbBC1L9.Five of them were distributed on chromosome 1,four of them were distributed on chromosome 2,and the remaining SbBC1L6 was distributed on chromosome 6.Besides,six members (SbBC1L1 and SbBC1L3,SbBC1 and SbBC1L4,SbBC1L2 and SbBC1L5) were generated by three-tandem replication events. All proteins encoded by COBRA genes had signal peptide and CCVS conserved domain at the N-terminus. Except for SbBC1L5,the other 9 members had the ω-site of the GPI anchor protein at C-terminus. Phylogenetic tree analysis showed that the COBRA genes were divided into two major groups.The first group contained two subgroups (A and B).The second group was constituted of four subgroups (C,D,E and F).Subgroup B was generated after differentiation of monocot yledonous and dicotyledonous plants,and belonged to the specific group for monocotyledonous plants.In subgroup C,COBRA gene loss occurred in monocotyledonous and dicotyledonous plants.The Ka(nonsynonymous substitution rate)/Ks(synonymous substitution rate) ratio indicated that all COBRA genes of Sorghum bicolor had experienced purification selection in the evolution process.Expression analysis showed that all COBRA genes had different expression levels in 11 tissues of Sorghum bicolor.SbBC1L1 had the higher expression in 11 tissues;three members (SbBC1,SbBC1L3 and SbBC1L4) had high expression levels in roots,pistils and new inflorescences treated by ABA(abscisic acid).While two members(SbBC1L5 and SbBC1L6) had higher expression levels in anthers tissues.