In order to investigate the heating-release behaviour of heated tobacco products, powdered Virginia tobaccos were decomposed at the temperature of 150, 200, 250, 300, 350 and 400 ℃ by pyrolytic technology respectively. It was shown that total volatiles increased with the increasing heating temperature. Compared with burned tobacco, only 5 percent of nicotine was released at 200 ℃, while 62% and 82% at 200 and 250 ℃ respectively. The heating temperature had obvious effects on the release of nicotyrine, myosmine, cotinine and 2,3'-dipyridyl. The content of nicotyrine reached the highest level at 350 ℃, up to 15.68% of the released nicotine content at the same temperature. However，the nicotyrine delivered from burned tobacco was only 35% of released nicotyrine from the heated tobacco at 350 ℃. Cotinine showed the similar changing behavior to nicotyrine. The released myosmine increased quickly with increasing temperature, compared to the burned cigarette, reached 2.57%, 18.78%, 39.39%, 65.62%, 85.72% of the content of delivered myosmine respectively. Heated at below 250 ℃, the aromatic substances were vaporized and no harmful or potential harmful substances formed basically. With the elevated temperature, the harmful substances formed and increased with the increasing heated temperature. The main harmful or potential harmful substances included phenol, methyl phenol, ethyl phenol, hydroquinone, 1,2-benzenediol, benzofuran derivatives, benzyl nitrile and benzenepropanenitrile.