Considering the trade-off between demand accuracy and relief allocation efficiency, a relief allocation problem based on demand updates is addressed. The rule of demand updating when the typhoon disaster occurred is learned by municipal bureau of civil affairs, thereby a method of demand updating, which uses the known demand to update the unknown demand, is proposed to model the addressed problem. Then the model is applied to an example of the post-disaster rescue after the destruction of typhoon. Computational results show the high velocity and accuracy of the model, and the optimal “decision-making point” is found to coordinate efficiency and equity well.