Abstract: The possibility of treating waste water from organophosphate pesticides factory with oxidation pond was investigated. The result showed that malathion, parathion, dimethoate, dimethyldithiophosphate and diethylthiophosphate can be degraded in algae-bacteria association system. The "half degradation time" of these compounds was 2, 5, 2, 42, and 62 days, respectively. Results of simulation experhnents of oxidation ponds in series showed that the removal efficiency of TOC, COD, and organic phosphate in waste water was 65.9%, 68.7%, and 67.8% respectively. The.effluent toxicity on fish decreased successively down the series of ponds; fish could grow and reproduce normaly in the third pond.According to the experimental results, parameters for the oxidation pound to treat waste water from GD Chemical Factory and for the project of YL region pollution control have been proposed.