Abstract: Macrobenthos can be used as good indicators for marine ecological quality status due to their lifestyle and Environmental stress ability. Recently multiple indices have been used to evaluate the benthic ecological status, because of the conceptual basis for each indices may rely on different assumptions and parameters, they were unable to give a consistent classification. In order to get a better evaluation of the benthic community health of Jiaozhou bay, we examined the changes of benthic communities over the past seven years, analyzed the main advantages and disadvantages of indices, established reasonable rules to selecte reference conditions, at last evaluate the selection effect by M-AMBI. Here we argue that setting reference conditions can reduce the error classification risk, helping us to identify the ecological status of Jiaozhou bay.