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Ramie as one of feature fabric crops in China, is an important materials in textile industry, which is mainly distributed in Hunan, Hubei, Jiangxi, Sichuan and Chongqing provinces. Nevertheless, many restrict factors are becoming challenges during ramie production; root rot nematodes is one of important diseases in ramie crops, which caused by Pratylenchus sp. The disease made increasing serious damage in the growth of Ramie, which led to degrade quality of fabric and limit to sustainable development in Ramie industry. Therefore the methods of integrated pests management in ramie growing areas are necessitate to control this disease. However, it is difficult to do that related research on nematode diseases is still not clear, So in this study, the rot root nematodes from the main ramie planting regions were sampled and isolated to research species identification, population genetic relationship, pathogenicity and population dynamic.The results achieved are as follows:(1) Through Morphology and Molecular technique, ramie root rot nematode from the four main ramie growing regions, including Yuanjiang, Hunan (named as HN-1), Yichun, Jiangxi(named as JX-2), Xianning, Hubei (named as HB-3) and Dazhou, Sichuan (signed as SC-4), were identified as Pratylenchus coffeae. The result of clustering analysis show that JX-2, HB-3and SC-4may have the same evolutionary origin for100% homologous, While homology between HN-1and P. coffeae from the populations of Hubei in China (HM469441) are belong to another branch with91%.(2) The pathogenicity of cultured P. coffeae using carrot callus as host were measured, and results showed that it had pathogenicity capability to ramie and affect to its normal growth.(3) The dynamics of natural population of nematodes of rhizosphere soil of ramie root rot of Yuanjiang, Hunan from2011to2012were investigated. As a whole, the density of nematodes population fluctuated drastically and had three emergence peaks in each year, which is larger in spring and summer than in autumn and winter. Besides the vertical distribution of nematodes, the density of nematodes population was increasing with increasing of depth of soil in a range of0～30cm. And the largest of nematodes population was shown in21～30cm of depth of soil, and the least of it was shown in0～10cm.
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