Abstract: Research on uncertain water quality model is done to improve the knowledge of the uncertain water condition,and an externally observed variable is always used to analyse the effect of uncertain conditions by regression or filter analysis.A neural network is embedded in to the water quality model to perceive the uncertain conditions of water environment,which will improve the precision of water quality forecast and enrich the uncertain water quality model.

Key words: time-delay； model BOD-DO； neural network, ； genetic algorithms； water quality model；