Abstract: In order to study characteristics of genetic variations of avian infectious bronchitis virus (IBV) in Guangxi Province of China, spike S1 protein, nucleocapsid （N） and membrane （M） protein genes of 7 IBV strains isolated in Guangxi between 2004 and 2007 were amplified by reverse transcriptase polymerase chain reaction (RT-PCR), cloned, sequenced, compared and phylogenetically analyzed. The results showed that many point mutations occurred within the S1 gene in all viruses and gene insertions and deletions occurred in majority of isolates. Amino acid sequence homology of S1 gene among the 7 IBV isolates varied from 74.2% to 98.7%. Deletion and insertion were not found in the N genes, but point mutations were found. Amino acid sequence homology of N gene among the 7 IBV isolates varied from 91.7% to 99.3%. Mutations and insertions occurred in M genes. Amino acid sequence homology of M gene among the 7 IBV isolates varied from 90.7% to 98.2%. Majority of Guangxi IBV isolates showed variations in S1, N and M genes comparing with H120 vaccine strain and S1 gene showed the biggest variation among the isolates. 7 IBV isolates were clustered into 2, 2 and 3 groups in the phylogenetic trees based on the deduced amino acid sequences of S1, N and M genes. The phylogenetic trees based on the N and M gene sequences do not follow closely the phylogenetic clustering based on the S1 gene for 4 out of 7 isolates. These results suggested that the variations were occurred in majority of Guangxi IBV isolates at S1, N and M genes. Point mutations, insertions and deletions had contributed to the genetic diversity and emergency of IBV variants in Guangxi Province. The present results indicated that the genetic variations may provide an explanation for the reasons of vaccines can’t protect effectively against epidemic strains in the field.