Based on analysis of the characteristics of modern brand agriculture on two dimensions of efficient expansion of scale and ability of continual payoff, the paper suggests four measurable indicators of modern brand agriculture growth: growth rate of sales revenue, growth rate of the quantities of practical farmers, growth rate of net profits and growth rate of practical farmers' income. Then, we analyze the mechanism of different factors driving modern brand agriculture growth and divide the growth system of modern brand agriculture into scale growth (SG) sub-system, benefit growth (BG) sub-system and social and economic development (SED) sub-system. Based on these analyses, a dynamics model framework of modern brand agriculture growth is founded to reveal the driving mechanism of modern brand agriculture growth and feedback relationships of factors. Finally, the key roles of government policy and social capital on sustainable growth of modern brand agriculture are discussed and emphasized.