To reveal the current classification problems(that)existed in Haemulidae species,partial sequences of nuclear DNA marker RAG2 of 33 species from Haemulidae,Nemipteridae and Scolopsis were determined in this study.Molecular phylogenetic trees were constructed using maximum parsimony(MP)and Bayesian inference(BI)methods and Scarus frenatus as outgroup.The result showed that three big clades were formed in the trees.8 genera of Haemulidae were grouped in one clade,Nemipteridae and Scolopsiswere grouped in another clade.Species of Scolopsisand Haemulidae could not form a monophyletic group in the trees.Based on the genetic distance data,the distance values between Scolopsis and Nemipteridae were much smaller than the values between Scolopsis and Haemulidae,indicating that Scolopsis had a closer relationship with Nemipteridae than Haemulidae.This result supported the view that Scolopsis might be included in the family Nemipteridae.In addition,the traditionally Haemulidae-classified genus Hapalogenys was not grouped within Haemulidae either.Three Hapalogenys species formed an independent branch and were located at the base of the phylogenetic tree,suggesting a distant relationship between Hapalogenys and Haemulidae.This result was consistent with the current view that Hapalogenys should be removed from Haemulidae.Within the inner species relationships of Haemulidae,Diagramma pictum was revealed to be located in the internal position of the Plectorhinchus group and sister to Plectorhinchus orientalis,and the speciePlectorhinchus cinctus was found to be first separated and positioned at the base of this group.The result suggested a very close relationship between D.pictum and Plectorhinchus and supported the view that D.pictum was classified to Plectorhinchus with the name changed into its original name Plectorhinchus pictus.