Asteriscus otoliths of carps were collected from the Baiyangdian shallow lake and the Miyun reservoir, whose water environments are completely different. The former has been seriously polluted whereas the latter is nearly pure and has experienced no pollution. The otoliths were analyzed by Neutron Activation Analysis (NAA) for microchemical characteristics as indicators to hydrochemical changes. The contents of Sr, Zn, As, Au, Ba, K and Na in the otolith from the Baiyangdian shallow lake are obviously higher than those from the Miyun reservoir. Linear Discriminant Function Analysis (STATISTICA) was uses to classify carp collection sites. The discriminant functions show the major differences between the two sites are the differences in concentrations of Sr, Zn, As and Ba. Moreover, the variation ranges of As,Ba,Sr and Na in otolith from the Baiyangdian shallow lake are relatively larger than those from the Miyun reservoir, which is in accord with the fact that a seasonal and temporal influx of industrial waste into the Baiyangdian shallow lake drainage area causes the precipitation of these elements in some otolith growth increments. The differences of these elements in otoliths from these two areas are consistent with those in the carp living water. These conclusions are of significance in study_ing indicators to hydrochemical environments.