Abstract: Under the background of one-size-fits-all patent system, the optimizing function of monetary reward system is outstanding with high operability and controllable targeting. Yet such system is made without complete theory and effective quantitative tool. The article employed elasticity, a commodity attribute of patent, to study the target of the patent monetary reward system and the way of its optimization. The article established the deadweight loss ratio evaluation model by studying the relationship between patent elasticity and deadweight loss. It is a new try to apply elasticity theory to patent field which may afford basis for deeply tapping the potentials, improving the relative efficiency, and reducing deadweight loss ratio of the patent reward system. The method developed in this article proved to be practical and effective after examining the performance of China Patent System empirically with the data of Chinese patent application since its implementation.