The invention provides an extra-high voltage alternating current drop point output project optimal selection method, and includes the steps of: preliminarily determining an extra-high voltage alternating current drop point 500kV transformer station range through balance of electric power and electric quantity, and preliminarily screening drop point 500kV transformer stations by evaluating influence on 500kV bus short-circuit current of a near region after an extra-high voltage drop point; based on the scale of extra-high voltage transmitting power, forming an extra-high voltage alternating current drop point output project scheme set, and further screening output project schemes by evaluating influence of each scheme on 1000 and 500 kV bus short-circuit current of extra-high voltage transformer stations; and determining a 500kV output project optimal selection scheme through short-circuit current and safety and stability checks. The extra-high voltage alternating current drop point output project optimal selection method provided by the invention can effectively remove unreasonable drop out output schemes by evaluating interactive influence of an extra-high voltage power grid and 500kV power grid short-circuit current of a near region, remarkably reduces unnecessary calculation workloads, the schemes have clear and definite directivity, and thus a reasonable extra-high voltage alternating current drop point output project scheme can be rapidly determined.