Abstract: Reasonable transmission pricing is an important basis for the construction of the electricity market. The improved transmission network use of system (TNUoS) charging methodology in UK is studied in this paper. The paper reviews the process of the transmission pricing reform in UK, summarizes the differences between the transmission pricing mechanisms before and after the improvement, and analyzes the improved DCLF ICRP model. The improved model is applied by using the example of 7-bus and IEEE 14-bus system, and it's effectiveness in guiding the generator and load investment is analyzed. Compared with the methodology before improvement, the improved methodology can effectively distinguish the TNUoS tariff of different power generation technologies, and promote the development of renewable energy, which can provide reference for the transmission and distribution pricing in China.