Abstract: Recently, thermal analysis is a useful technique to study the kinetics of decomposition reaction. We used this technique to studythree kinds of organophosphorus pesticides——roger, dipterex andparathion-methyl and obtained kinetic equations of the theremal decomposition.These pesticides may decompose more or less readily in storage conditions. The rate of decomposition increases at higher temperature, especially to parathion-methyl, and an explosive violence would occur at certain temperature.In order to control the thermal decompositions of these pesticides either in storage or in production, we studied their decomposition kinetics and mechanisms and estimated the "stable life" at some lower temperature.