The invention relates to a line project cost estimation method based on power transmission and transformation project cost design elements. The method comprises the following steps: determining input parameters: project conductor cross sections, a loop number, a meteorological combination, a project terrain proportion, market prices of conductors and tower materials, requisition and cleaning expenses of a construction site, a corridor complexity coefficient and a k value; quantifying qualitative indexes with a dummy variable multiple regression model; substituting the parameters such as the project terrain proportion, the meteorological combination and the corridor complexity coefficient into corresponding Y'<500kV single loop>, Y'<500kV double loop>, Y'<220kV single loop> and Y'<220kV double loop> formulas respectively to perform a calculation; substituting the market prices of the conductors and the tower materials into an existing deltaY price factor formula to perform a calculation; substituting an amount per kilometer of the requisition and cleaning expenses of the construction site into a deltaY policy factor formula to perform a calculation; and obtaining a static investment according to calculation results in the steps above. Through adoption of the method, an inherent law of the influences of various factors on a project cost level can be revealed; a project cost can be pre-estimated scientifically before the execution of design work; and high accuracy is achieved.