Brand building of agricultural products is conducive to expanding market, raising sale price, boosting market competence and further increasing the income of the peasants. The survey on 9 prefecture cities of Guizhou shows that brand building is helpful to market expansion of the agricultural products but the effect of agricultural enterprises on peasants income growth needs to be improved. Currently the brand building of Guizhou’s agricultural products and peasants’ poverty alleviation are short of effective interactive mechanism, and have the problems such as dim brand consciousness, insufficient brand extension, immature scale effect, low brand marketing, geographical signs abusing and so on. Thus, the interactive mechanism for brand building and poverty eradication should be set up and perfected by intensifying brand consciousness, by consolidating brand expansion, by enlarging scale effect, by optimizing marketing methods, and by standardizing brand management, and the effect of poverty eradication can be raised by sufficiently making use of brand value to drive the related industries to develop.