Abstract: Abstract：Membrane(M) protein gene of IBVSX16 strain isolated in isolated in Shanxi was sequenced and analyzed. The results showed that the M gene of isolate was composed of 681 nucleotides, encoding polypeptide of 226 amino acid residues. Variations of the deduced amino acids of M gene mainly occurred at positions 2 to 17, deletion and insertion was not found in the N gene of IBVSX16 comparing with that of the IBV strains H120 and LX4. A phylogenetic tree based on amino acid sequences of M gene of the 19 IBV strains showed that these strains were classified into five distinct clusters. IBVSX16 strain was in cluster III. Most of the Chinese IBV strains were included in clusters III and IV，forming distinct phylogenetic groups in China.． Key words：infectious bronchitis virus；membrane gene； Genetic variation