Given the continuous expansion of the AC/DC power grid interconnection scale and capacity connected with grid generated by new energy, the generation side is facing an increasing risk of active power shortage. This then brings higher requirements for the implementation reliability of the third line of defense low frequency load shedding scheme in a local power grid. There are shortcomings of the round load adjustment methods for the existing implementation scheme, such as low qualified rate, poor stability and poor timeliness. Thus this paper proposes a round load adjustment method considering the load characteristics of distribution network lines. Based on the low frequency load shedding scheme, the implementation evaluation indices are designed, and an 0-1 integer programming optimization model of implementation scheme line adjustment is established with the induction function that considers the similarity and distribution network line load curve fluctuation. Then the flow design of the algorithm is realized. Empirical analysis based on the actual project shows that the proposed method is better than the existing methods in terms of round implementation qualification rate, stability and application time. By establishing the evaluation and decision-making system of the implementation scheme of the low frequency load shedding, the intelligent level of the implementation management is effectively improved. This has significance for the adjustment and optimization for the implementation scheme of the low frequency load shedding of the local power grid. This work is supported by the Science and Technology Project of the Headquarters of State Grid Corporation of China (No. 52199720003Q).