Bacterial leaf blight disease is counted as one of the most important bacterial infections in rice (Oryza sativa L.) caused approximately 50 % yield losses. This disease is cause from the infection of Xanthomonas oryzae pv. oryzae (Xoo) that high outbreak in the rice field in the north and northeast part of Thailand. The isolation and study genetic diversity of bacteria is the important information for rice breeding program to generate the new variety of rice which resisted to the bacterial leaf blight disease. This project collected rice leaves from 16 districts in Chiang Mai and can isolated 70 bacterial samples. The colony characteristic and grams staining revealed 26 bacterial isolates were likely to be the Xanthomonas oryzae pv. oryzae, a pathogen of bacterial blight disease in rice. The PCR amplification of rpoB and gyrB was successfully identified from total 15 samples. The DNA sequencing data from 2 primer pairs were used to study the genetic diversity among these 15 bacteria samples. The Maximum Likelihood tree was constructed using MEGA6 program which divided bacteria isolates into 5 groups. Pathogenicity test revealed 2 rice varieties which are Khao Dawk Mali 105 and Niaw San-pah-tawng were successfully infected by the isolated bacteria. The bacterial isolated from this study will be useful for further study in order to analyze the infectivity in rice plant and identified the protein response to rice resistant to the bacterial pathogen caused the bacterial leaf blight disease.