The main objectives of this study is to :¡]1¡^probe into relationship of larval fish communities and environmental water factor in Tan-sui River Estuary, and observe assemblages of larval fish within different time scale¡F¡]2¡^to compare the results of DNA barcode with mophorlogical identification in larval and juvenile¡F¡]3¡^conjecture the recruit phase & the early life cycles of DNA indentified fish groups associated estuaries in Tan-sui. It shows that recruitment family, such as Scorpaenidae, Engraulidae, Sciaenidae, Sillaginidae and Gobiidae are the main fish have significant differences between larval fish community and the four seasons in Tan-sui estuary. Besides, statistical informations show community distribution and most environmental factors have significant differences, but temperature is the most. We compare the communities of twenty years ago, spring, autumn or summer are the opportune time of recruitment, 72 and 31 families of fish larvae were collected over past five and twenty years ago respectively, it shows that Tan-sui estuarine environment have been improved. We used 96 COI sequences in DNA indetification. Comparing the results of specimens identification between DNA barcoding and different morphological resolution power, DNA barcoding could up to the lower level than the tradiontional way. And after counting, the success rate of DNA identification was higher than different morphological resolving power¡Fthe numbers of mophological type are higher than the taxa after DNA indetification, it means that many morphological characters are not constant in early developmental stage, and DNA barcoding can be a useful tool to assist in promoting the success rate of the traditional way. Comparing with references, 34 indentified by DNA Barcode can conjecture recruit phase & early life cycles, most of these specimens are categorized to¡unondependent marine fish¡v, and the others are¡udependent marine fish¡v, but in fact, some of¡utrue estuarine¡v¡B¡ufeshwater¡vand ¡udiadromous¡vspecies can be indetified by morphology, it was due to the incompletion of the sequence database or sampling error. We should be able to understand the early life history of fish and the role of local habitat for the resources conservation and managenment in the future as long as we collect more complete COI database.