The invention provides a hierarchical modular power network planning scheme optimization method. The method includes the steps that (1) a county-level planning unit serves as a minimum unit of a calculation system of the method, and the calculation problem of the capacity-load ratio of an interconnected area is solved by means of division coefficients; (2) a calculation system is built on the basis of the method, and imbalance degrees, such as the largest load imbalance degree, the coincidence factor imbalance degree and the capacity-load ratio imbalance degree, of indexes in a target area are obtained quantitatively; (3) sensitivity of the capacity-load ratio to an item is analyzed, the concept of a sensitivity coefficient is put forward and accordingly influences of operation of the item on the capacity-load ratio of the area are weighed; (4) a load prediction method in a new planning period is put forward, according to the method, a hierarchical modular analysis concept is adopted, firstly, the whole load prediction work is divided into different levels of load prediction according to a certain rule, the natural growth rate of the load of each level is solved level by level, and ultimately the largest load of each level of a power grid at the end of the planning period is solved from bottom to top.