The invention discloses a method for measuring the strength adjusting capacity of a multileaf collimator. Based on the method, the invention discloses a leaf designing system of the multileaf collimator. The leaf designing system comprises a data input unit, a problem describing unit, a problem solving unit or a problem simplifying and solving unit, and a data output unit, wherein the data input unit is used for inputting large-sample-capacity radiation field intensity matrix data collected from a clinical data system; the problem describing unit is used for establishing a physical model for describing an optimization problem; the problem solving unit or a problem simplifying and solving unit are separately used for solving the optimization problem through an optimization technique or appropriately simplifying the optimization problem and then solving the optimization problem; and the data output unit is used for outputting optimal designing data to a processing unit of the multileaf collimator. The application also discloses a leaf designing method of the multileaf collimator, the multileaf collimator leaves and the multileaf collimator. Through the adoption of the method for measuring the strength adjusting capacity of the multileaf collimator, the leaf designing system of the multileaf collimator, the leaf designing method of the multileaf collimator, the designed leaves andthe designed multileaf collimator disclosed by the invention, the strength adjusting capacity of the multileaf collimator is improved, and the purpose of improving the strength adjusting planned quality is achieved.