Abstract: In order to investigate the effect of polysaccharides extracted from the northwest region plants on the quality of cigarettes, the moisture content and pH in cigarette mainstream smoke of propylene glycol, blank (water) and 6 kinds of plant polysaccharides were analyzed by GC and potentiometric titrator.The result showed that:adding plants could significantly increase the moisture content of mainstream smoke.The moisture of cynomorium polysaccharides added cigarettes in particulate matter of mainstream smoke increased by 31.3%, 44.3% respectively compared with propylene glycol and blank samples.Adding plants polysaccharides could significantly reduce pH of cigarettes in mainstream smoke, but decreased slightly.The results showed that northwest plant polysaccharides such as Hippophaerhamnoides L.polysaccharide;Potentilla anserine polysaccharide, could significantly reduce pH and improve moisturecontent in cigarette mainstream smoke.