Abstract: 【Objective】In order to study the distribution patterns of Echinocloa species in late rice fields in tropical areas of Guangxi and provide basic data for the control of barnyard grass, biology and ecology research on barnyard grass.【Method】Barnyard grass was the objective.Barnyard grass in the laterice fields of which located in the tropical region such as Nanning, Beihai, Qinzhou, Wuzhou, Guigang, Yulin, Baise and Chongzuo were investigated and sampled with the five point sampling method in October, 2019 and October, 2020.There were 112 investigation points and 672 plots.The occurrence of barnyard grass was surveyed by seven grade visual method on each point.The Shannon-Wiener niche width and Pianka niche overlap value in the Levins method were used to analyze the niche dynamics of barnyard grass in paddy field.【Result】The results showed that nine species of Echinocloa species were observed in late rice fields of Guangxi, they were E.cruspavonis, E.glabrescens, E.caudata, E.crusgalli var .zelayensis, E.colonum, E.glabrescens, E.crusgalli var .mitis, E.crusgalli var .Breviseta and E.crusgalli var .praticola. The occorrence frequency of E.crusgalli var .mitis was the highest(98.21%), followed by E.crusgalli var .zelayensis(93.75%), and those of E.caudata, E.glabrescens and E.colonum were low, which were all lower than 40.00%.In Baise, Qinzhou and Wuzhou, E.crusgalli var.mitis was mono-dominant among Echinocloa species on rice fields, while in Beihai, Chongzuo, Guigang, Nanning and Yulin, E.crusgalli var. zelayensis was dominant species.Among the nine Echinocloa species observed, E.crusgalli var.mitis showed the largest niche breadth(2.847), followed by E.crusgalli var.zelayensis(2.614).Niche overlaps between E.crusgalli and E.cruspavonis were the highest, that between E.colonum and E.glabrescens were the lowest, those between E.colonum and other species were low.【Conclusion】Echinocloa species in late rice fields of Guangxi are abundant, and the dominant species of barnyard grass are different in different rice fields.Specific control measures should be taken for different species of barnyard grass in production.