Abstract: Chlorine is one of trace elements in coal, which do harm to environment badly. It is of significance for the removal and control of chlorine in coal that the isolation characteristic of chlorine in coal was studied. In this paper, test data were fitted by using Boltzmann function, and model of chlorine removal was built on the process of coal pyrolysis. Relative error between model data and test data was low t10, t50, and t90 were put forward to compare to the temperature at which chlorine removal was 10w%, 50w% and 90w% respectivelyΔt80 was used to describe the primary temperature range of chlorine removal during pyrolysis. On the basis of these, the experimental data showed that the pyrolysis temperature of coal was different when the chlorine removal changed from 10% to 90%. Chlorine removal from coal was above 90w% at the pyrolysis temperature of 900 ℃.