The thermooxidative decomposition and its kinetics of chlorinated natural rubber (CNR) from latex were studied by thermal gravimetry (TG) analysis and TG coupled with fourier transform infrared spectroscopy (FTIR). The thermooxidative decomposition of CNR is a two-step reaction. The first step is a reaction of dehydrochlorination of which the reaction order (n) is 1.1, the reaction activation energy (E) increases linearly with the increment of heating rate (B), and the apparent activation energy (Ev) is 101.7kJ/mol. The initial temperature of weight loss Tv=1.29B + 248.7, the final temperature of weight loss Tr=0.86B + 312.4, and the temperature at maximum weight loss ratio Tp = 1.05B + 286.2, Cp which is the decomposition ratio at Tp, is not affected by B, and its average value is 38;, c which is the decomposition ratio at T is also not affected by B, and its average value is 60;. The second step is an oxidative decomposition reaction of the molecular main chain, and the value of n is 1.1, E increases linearly with the increment of B, Ev is 125.0kJ/mol and the relation between B and T is similar to that of the first step, C approaches 100;.