Sweet protein thaumatin is the sweetest substance known so far.Thaumatin has many features that make it attractive to food and feed manufacturers.Its nucleic acid sequence and amino acid sequence have been reported.Structure analysis showed that thaumatin has high stable tertiary structure. The substance mediated between thaumatin and microvilli of the taste bud pores has been found.The exact function of thaumatin and thaumatin like protein is still not clear. Thaumatin has been expressed in some procaryotic and eucaryotic expression systems, but no satisfied products can be got through the way of gene engineering by now.