With the development of economy and society, people have realized the relation between smoking and health and controlling smoking has become a mai n trend. For various reasons, some people have the interest on smoking; the only choice to them is possibly to smoke lower dangerous and more secure cigarettes. So it is very important to research the harmful chemical substances in cigarett es and reduce it. This article illustrates the harmful chemical substances in ni cotine of cigarettes and its influence to body's health so that it can supply t he theoretical basis for producing secure cigarettes.