Abstract: At present， Polo （Probit and Logit Analysis） software has been widely used and internationally accepted for analyzing the bioassay data. In order to show the advantage of Polo software for comparing the pesticide toxicity， the toxicity data of triazophos and chlorantraniliprole on Chilo suppressalis has been analyzed by Polo software. The parallel and equal hypothesis test has been done and the 95% confidence limit of lethal dose ratio was used to determine whether the differences between the pesticide toxicity were significant. Then， the results analyzed by Polo software were compared with that calculated by the traditional method， which use the overlap of 95% confidence limit as a criterion of significant differences. The result showed that the pesticide toxicity data analyzed by Polo software were more accurate and reliable. Therefore， this method is suitable for comparing the toxicities of different pesticides， resistance levels， and analyzing the data of pesticide synergist tests.

Key words: pesticide toxicity, lethal dose, slope, Polo