Abstract: Five hundred and twenty bp nucleotide sequences in the 5' terminal part of the mtDNA D-loop control region of 33 Carassboides cantonensis from 2 populations渊Nandujiang and Wanquanhe冤of Hainan island were determined. 5 mutation sites defined 5 haplotypes, of which 4 sites were parsimony-informatic, and no insertions and deletion was found, transition transversion ratio was 4. The haplotype diversity of Wanquanhe and NanduJiang group were 0.6762(依 0.1006) and 0.6993(依0.0435), respectively, and the nucleotide diversity were 0.00249(依0.001849) and 0.00260(依0.001887), respectively, both at a relative low level. Neutral tests showed that the Fu's Fs wasn爷t significant negative (Fu爷s Fs=0.288袁 P>0.1), and mismatch analysis wasn爷t obvious unimodal, which suggested that Carassioides cantonensis in Hainan island might not have experienced rapid population expansion and they were demographically stable in the history. No significant genetic differentiation was found between the 2 groups (Fst=0.03638, P>0.1), so they could be maintained as a single management protection unit.