The invention discloses a rockfall prevention driven flexible protective net system designing method based on the energy matching principle. The rockfall prevention driven flexible protective net system designing method comprises the steps that 1, the energy consumption rate matching principle of components of a driven flexible protective net structure is established; 2, preliminary model selection and arrangement are performed on the components of the driven flexible protective net structure; 3, an explicit dynamics computation model capable of considering features such as the initial perpendicularity, large sliding of a supporting rope, large rotation of a supporting column and large deformation of an interception net is built through a finite element computing method; 4, impact loading is performed on the computation model, and dynamics response of the structure under the impact effect is analyzed; 5, structural design of the driven flexible protective net is performed. According to the method, the design principle of energy matching is adopted, both the force balance and the energy balance are considered, and the design is more scientific and reasonable; the component strength, stability, deformation and the like are used as design verification control indexes, and both the component design bearing capacity safety storage and the applicability of the protective net structural overall interception effect are considered.