The results from pot experiment, plot test and pharmacelltical product selection by sifting were showed that the phenoxy-hydroxy-acid herbicides such as 2,4-D-Na, 2,4-D butylate and Banvel were highly active to distress weed Mikania micrantha, effective to keep off M. micrantha and control its growth. The best results of the different application parts were both in the top part and the middle parts of the plants. The effects could be improved by adding SDS into phenoxy-hydroxy-acid herbicides. M. micrantha had different sensibilities to phenoxy-hydroxy-acid herbicides in different development stages from seedling to peak of growing season. The drug resistance can be improved from early flowering growth; MCPA-Na was unefficient in controlling M. micrantha.