For the past few years, the problem of higher food prices has aroused the world's concern We have long worried about agriculture, treating it as the foundation of the national economy, but regret at the lack of support for empirical evidence By analyzing the data of the world bank in 2006，the author estimates the influence of agriculture It is found that the marginal utility of agriculture is always positive although decreases successively gradually On the eve of economic takeoff , the lower middle income countries have a bigger positive marginal utility of agriculture than others, so they ought to insist on the strategy of agriculture makes perfect