Thermooxidative decomposition and its kinetics on chlorinated natural rubber (CNR) from latex are studied by thermal gravimetry (TC) analysis and TG coupled with FTIR spectroscopy. The thermooxidative decomposition of CNR is a two-step reaction. The first step is the reaction of dehydrochlorination of which the reaction order (n) is 1.1; the reaction activation energy (E) increases linearly with the increment of the heating rate (B), and the apparent activation energy (E-o) is 101.7 kJ/mol. The initial temperature of weight loss (T-o) is 1.29B + 248.7, the final temperature of weight loss (T-f) is 0.86B + 312.4, and the temperature at the maximum weight loss ratio (T-p) is 1.05B + 286.2. The decomposition ratio at T-p (C-p) is not affected by B, and its average value is 38%. The decomposition ratio at T-f (C-f) 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. The value of n is 1.1, E increases linearly with the increment of B, E-o is 125.0 kJ/mol, the relation between B and T is similar to that of the first step, and C-f approaches 100%.