Abstract: Quantitative survey and research on barnacle species attaching to mangroves,the relationship between barnacle quantity and biological and ecological factors,barnacles harm to artificial young mangrove trees and their chemical control was conducted.The results showed:there existed two barnacle species on artificial young mangrove trees,namely Balanus reticulatus and Chthamalus sinensis.The barnacles quantity attaching to mangroves had positive correlation with their habitat seawater salinity,tide inundating depth and tide flooding ratio. On the other hand,the decortication of trunk of some mangrove trees such as Kandelia candel,Sonneratia caseolaris and other marine algae’s attaching to mangrove tree trunk decreased barnacles’ quantities to some degree.Large scale of barnacles attaching to young mangrove trees (1～3 a) reduced the increment of tree height and trunk diameter,caused tree trunk in deformation and even death. Low toxic chemicals blended with red paint(1:1 000～2 000) was smeared on young mangrove tree trunks to which barnacles attached,the control effect was up to 100 percent;whereas low toxic chemicals diluted in water was sprayed on the trunks,branches and leaves of young mangrove trees,the control effect was not obvious.