Up to the present, there is a lack of an acknowledged method to evaluate the economic benefit on rubber tree tapping system synthetically. In this paper, it was put forward and demonstrated that the economic efficiency was the perfect quantity index to evaluate the economic benefit of different tapping system. Economic efficiency index could be used to judge how excellent or inferior one tapping system was among different systems, because the factors both production value and production cost were be considered in it. The calculating formula of economic efficiency was: Ei/o=[Yi+K1(Ai/Ao-1)-K2(Bi/Bo-1)] x 100;. In the formula, Ei/o--the economic efficiency index of i tapping system comparing to control tapping system (o). Yi--unit area yield of dry rubber under i tapping system. Y--unit area yield of dry rubber under O tapping system (control). K1--ratio of tapping cost comparing to selling price unit weight. A1--working efficiency under i tapping system. Ao--working efficiency under o tapping system. K2--ratio of tapping assitant material cost comparing to selling price unit weight dry rubber. B1--unit production cost of tapping assistant material under i tapping system. Bo--unit production cost of tapping assistant material under 0 tapping system. Using this formula, not only the degree of excellence could be compared among different tapping systems, but also the appropriate system could be selected according to the change of product price and labor price. The calculating course and method were particularized in the paper.