Due to the effect of significant environment on the volatile and the stability of organophosphorus pesticides

the accuracy and the comparability of identification are weakened using electronic nose.In order to ensure the reliability of the results of the analysis

effective analyzed data are obtained by finding out the starting point of sensor response.A new feature extraction method named as"slope area ratio"method is proposed on the basis of the investigation of the integral method and the mean-differential coefficient value method

which are two kinds of popular feature extraction method.Principal component analysis（PCA）and BP neural networks are used to classify the two types of pesticides.The results show that the slope-area ratio method is the most effective method compared with other two feature extraction methods in the classification of organophosphorus pesticides.