Abstract: SIX genes were first detected in the xylem sap proteome of F.oxysporum f. sp. lycopersici (Fol)-infected tomato plants, and had been successfully used to differentiate the three races of F.oxysporum f. sp. lycopersici. Some SIX-genes have been reported in Fusarium oxysporum f. sp. cubense (Foc) which is the ca usal agent of fusarium wilt of banana. To differentiate the races or subtypes of Foc, the SIX7 gene was analyzed.Based on the known SIX7 gene sequences, primers were designed and synthesized. And PCR and sequencing approach were used to detect the SIX7 in a collection of 56 Foc isolates from different domestic banana growing areas and from Australia or South Africa. And also the specific of SIX7 gene was screened with totally 39 isolates including eight other F.oxysporum formae speciales and non- pathogen F.oxysporum and F. monilifarme and F.solani and some other genus pathogens of tropical crops. The study found that the designed and synthesized SIX7 gene primers were only amplified to a 663 bp target band from the tested subtropical species of Foc race 4 (ST4). Together with the known Foc4 specific primers Foc-1/Foc-2, Foc-SIX7 gene could be allowed to differentiate subtropical race 4 from tropical race 4 isolates. It would provide a quick molecular identification method to distinguish Foc4 subtypes in disease affected banana plants, and would guide banana farmers to take timely and effective measures to prevent and control banana Fusarium wilt disease.