Introduction  Under the background of electric reform， the pricing mechanism of transmission price for special projects across provinces has been clarified. Under the overall requirement of lowering the general industrial and commercial electricity price in the country， the transmission price of Power Transmission from West to East Project of China Southern Power Grid Company Limited experienced two downward adjustments in 2018－2019. Clarifying the price flexibility space of the Power Transmission from West to East Project has become the focus of attention of the government and transmission companies.

  Method  Based on the pricing experience of domestic and international transregional transmission prices， this paper combines the asset allocation method， the operating period electricity price method， the permitted cost + income and other methods， measuring and comparing the cost of electricity， the accounting price of the pricing plan and the government's issued electricity price of the Power Transmission Project from West to East.

  Results  Through the research and calculation of transmission price， the pricing mechanism and flexible space of the Power Transmission Project from West to East has been fully understood.

  Conclusion  Based on the actual engineering empirical analysis， it is proved that the calculation method is reasonable and effective， which can provide a basis for the government to reasonably formulate the transmission price and the investment decision of the transmission company.