Abstract: Based on the data collected from 43 zoobenthos sampling sites (7 reference sites and 36 impaired sites) in Huaihe River Valley from July -to Auguest, of 2010, analysis was done of seventeen candidate biological index values for distribution range, correlations and discriminability, and meanwhile, total number of taxa, number of EPT taxa, proportion of sensitive groups and biotic index were screened out to form a B-IBI index system for the Huaihe River Vallley. 3 -point system, 4- point system and ratioing technique was used separately to uniformized dimensions of various parameters and B-IBI value was then the sum of the values of various component indices of the system. Discriminatory power analysis shows that the B-IBI values worked out with the three methods were all quite high in discriminability (Q_I=3), moreover, the three methods were highly correlated (r > 0.90). Health evaluation criteria were established separately based on 25 quantile of the distribution of B-IBI values of the reference sites and 95 quantile of the distribution of all the sampling sites, and comparison was performed between the three methods in accuracy of the evaluation. Results show that the health evaluation criteria established on the B-IBI values of all the sampling sites and dimensions of various parameters uniformized with the 3-point system and 4-point system  are superior to that based on the ratioing method. Therefore, the commonly used 3-point system method was selected for use to establish health evaluation criteria suitable for the Huaihe River Vvalley. B-IBI >19.2 means healthy; B-IBI varying in the range of ＞14.4-19.2, sub-healthy; B-IBI in the range of ＞9.6-14.4, fair; B-IBI in the range of ＞4.8-9.6, poor, B-IBI≤4.8, extremely poor. Evaluation of the 43 sampling sites shows that 6 are in healthy state, 5 in sub-healthy state, and the other 32 in unhealthy state.

Key words: B-IBI, health evaluation, zoobenthos, Huaihe River Valley