By selecting different categories of ecological data in statistical analysis,a total of 20 empirical models were constructed for DO prediction withinearthern ponds,for indefinite period of time.The more variables involved,thehigher the power of interpretation of the model.A general survey of allmodels showed that DO at any time t deeply depended on a dummy variableZ,and the DO level at a previous time.Light intensity was the most consistantand significant environmental factor controlling DO fluctuation.Others factorsincluded pH,water temperature,carrying capacity,paddlewheel,wind action,and Secchi disk visibility.Effects of salinity,light extinction coefficient andwater depth were not significant.