Abstract: In order to investigate the rules of ammonia formation from nitrogenous compounds in tobacco during cigarette combustion, the effects of smoking temperature, oxygen content in and flow rate of smoking atmosphere, and the heating rates on the ammonia formation from the combustion of main ammonia precursors in tobacco were studied with a cigarette smoking simulator. The results showed that: 1) Smoking temperature, oxygen content in smoking atmosphere and heating rate obviously affected the ammonia formation from the combustion of protein, ammonium oxalate, proline and asparagine, while the influence of carrier gas flow rate was slight. 2) Lower oxygen content in smoking atmosphere, higher heating rate and moderate circumstance temperature could inhibit the formation of ammonia from pyrolysis of tobacco or ammonia's precursors.