Recently there are many different types of the researches on organophosphates. The results on neurotoxicity can make people find out the treatments on organophosphate-poisoning. The parathion and chlorpyrifos are two typical types of organophates to be examples of the researches. The aim of researches is to find out the neurotoxicity of organophosphates to the mammalian animals. In vitro model, the aggregating cell culture of fetal rat telencephalon, has been used to investigate the different factors of neurotoxicity. The results show that the inhibition of parathion to acetylcholinesterase (AChE) is more effective than the chlorpyrifos. It shows that 2qthe in immature culture, the effect of parathion tends to be more effective. The cell culture treated by parathion is more sensitive than the neuro-specific enzyme activities. On the contrast, the chlorpyrifos have week induced reaction and are only effective on the influenced concentration. In general, the immature culture is more sensitive to OPs treatment than the differentiated culture. Moreover, the general cytotoxicity of chlorpyrifos and parathion are both low. The results show that there are many differences between neurotoxicity of parathion and chlorpyrifos. By taking look of the differences, the separative treatment can be found in the future.