Abstract: Tricholoma matsutake polysaccharide was taken as the main objective,and its effects on the lactic acid fermentation of Lactobacillus bulgaricus and Streptococcus thermophilus strains and yogurt quality were investigated by determining the triratable acidity,water- holding capacity,texture,total number of lactic acid bacteria,sensory of yogurt. The results indicated that there was an inverted U- shaped relationship between the adding amount of tricholoma matsutake polysaccharide and the growth of lactic acid bacteria. When the adding amount was lower than 0.06%,the growth of lactic acid bacteria was significantly promoted( p < 0.01),and when the adding amount was 0.04%,the promoting effect was the best.Meanwhile,tricholoma matsutake polysaccharide had also shown some inhibitory effects on the ability of producing acid of lactic acid bacteria and could thus lengthen the after acidification process of yogurt. With the increase of its concentration,an inverted U- shaped curve was shown in the water- holding capacity,texture and sensory evaluation scores of yogurt. The quality of yogurt was the best when 0.04% tricholoma matsutake polysaccharide was added. In conclusion,the best promoting effects of lactic acid bacteria growth and yogurt quality were found when the adding amount was 0.04%.