Oryza meyeriana (Zoll. & Moritzi) Baill. is a wild relative of cultivated rice. O. meyeriana is reported to exhibit high resistance or immunity to bacterial blight (BB), a disease caused by Xanthomonas oryzae pv. Oryzae (Xoo). To fully understand the BB resistance of O. meyeriana across multiple distribution sites in Yunnan, China, 87 accessions of 29 O. meyeriana populations were inoculated by artificial leaf cutting with the Xoo virulent strain CX28-3 isolated from rice in Yunnan. The diversity of resistance and habitat of each accession were then analysed. The results showed that resistance was variable. Among the 87 accessions, only 20.7% were resistant (12 resistant and 6 highly resistant), 37.9% were susceptible (9 highly susceptible and 24 susceptible), and the remaining 41.4% (36 accessions) were moderately resistant; no accession tested displayed immunity to CX28-3. The variation of resistance among populations is higher than within a population. The 29 populations of O. meyeriana were divided into categories according to administrative region, river system, longitude, latitude, altitude and climate factors. The resistance distribution and diversity index of the 29 O. meyeriana populations were calculated. The resistance of O. meyeriana accessions was shown to be quite different among the five administrative regions. The resistance from Xishuangbanna was the strongest, followed by Pu’er, Dehong, and Lincang, while that from Baoshan was the weakest. The diversity index of resistance is highest in Pu’er (1.13), followed by Dehong (0.95), Baoshan (0.69), Lincang (0.67), and Xishuangbanna (0.64). Correlation analysis showed that geographical and climatic factors impacted the resistance of O. meyeriana. There is a highly significant positive correlation between latitude and disease index. There is also a significant positive correlation between altitude and disease index. These results indicate that accessions of O. meyeriana at greater latitude or altitude are more susceptible to BB. By cluster analysis of the geographical and climatic factors of the O. meyeriana distribution sites, the 29 populations were classified into five groups with differences in resistance. O. meyeriana is considered nearly immune to BB, but susceptible accessions were found for the first time in Yunnan Province, China.