Abstract: To control tobacco black shank disease rationally, reduce resistance, 34 strains of Phytophthora parasitica var. nicotianae were isolated from 6 region of Yunnan province and all isolates were determined their resistance to metalaxyl. The results indicated that of all tested isolates, there were 12 high resistance, 5 middle resistance and 17 low resistance isolates respectively. The islates fungicide resistance from different region was different obviously, the highest resistant isolate come from Wenshan and Yuxi region, Zhaotong and Qujing isolates had the lowest resistance among all tested isolates. The evident disparity of high-resistance, mid-resistance and low-resistance isolates ratio was exist at different region. 113# from Chuxiong Shuangbai was the highest metalaxyl resistant isolate,and the lowest resistance isolate 218# come from Weishanof Dali. The EC50 of 34 Phytophthora parasitica var. nicotianae isolates against metalaxyl was 0.0148μg/ml in average, was in the range of 0~0.053μg/ml.