In building a new On-line Multi-factor Monitoring System (OMMS) of Water Accidental Pollution Events (WAPE) based on the behavioral responses (BR) of aquatic organisms, the effects of physi-chemical factors (PF) such as temperature (T), turbidity (TUB) and pH on BR of Daphnia magna and medaka (Oryzias latipes) were discussed with Biological Early Warning System (BEWS). The results suggested that when T was lower than 5°C, BR of D. magna and medaka would be inhibited in 5 hours. If TUB was more than 50NTU, the behavior strength (BS) of D. magna would decrease to about 0.3 after 10h exposure, the effects on medaka would be much weaker in 24h than D. magna. If pH is lower than 5.5 or higher than 9, negative effects on BR of both aquatic organisms would happen in 15h. Therefore, a new OMMS was built for the purpose of environmental management of WAPE, which included BEWS and PF Monitoring System (PFMS).