The paper takes cash at hand more than the futures hedging capital requirement as the restraints of the Sharp hedging ratios to set up the optimal hedging model of single future based on capital constrain.

We find that farmers with different income have different capital demand;small capital is the principal part of farmers demand;the income level of farmers have the positive correlation with the capital demand and have the negative correlation with the frequency of borrowing.

To realize the aim that was decide by national economy and plan of social development, must forecast and analyse fund demand correctly and ensure to carry on the aim smoothly.