Combustion behavior of cigarette paper containing different content of combustion improver was investigated in order to provide direct experiment data to elucidate lower components in cigarette smoke caused by combustion improver in cigarette paper. The content of the combustion improver was denoted as "organic" potassium index and determined by atomic absorption spectroscopy and ionic spectroscopy. The combustion process obtained by simultaneous thermal analysis was divided into four stages: weight loss due to loss of absorbent water, decomposition of the cellulose, the oxidation of the cellulose char and decomposition of calcium carbonate. Combustion improver reduced the temperature of cellulose decomposition 3-12 K and contributed to oxidation of the cellulose char. Ignition point was gained and reduced 3-8 K by combustion improver. Above results were further verified by samples from two other cigarette paper factories. Mechanism of lower components in cigarette smoke by the combustion improver in cigarette paper was discussed.