The pyrolysis of cellulose was studied using a novel CCDR in which tar and gases can be fractionated according to the reaction time. Similar trends of evolution behavior were observed for both tar and low-molecular-weight gases in the pyrolysis of cellulose at 673 K. The evolution of tar and low-molecular-weight gases achieve a peak at 20-30 s, converting depolymerizing cellulose to nascent char. The dehydration of nascent char produced by depolymerization and devolatilization was found to take place after the devolatilization is completed.