Through an extensive investigation,the following tasks are accomplished: (1) The chief agroclimatic variables of the Yixing hilly area are found to be in good agreement with normal distribution and a method of computing the accumulative negative temperatures by observed maximum and minimum temperatures for predicting frost injury is developed. (2) Each of the agroclimatic variables is analyzed and appraised with reference to the agroclimatic indices for citrus trees,tea bushes and bamboos. (3) Payment function for each crop is established,leading to a quantitative agroclimatic decision plan,which considers agroclimatic historic information,future prediction and economic benefit by Bayes decision method.