The present study develops a method called the energy equal partitioning method. This method divides all the solid angles of a radiating source properly so that the energy carried by the beams within each small range of the solid angle are equal. The fraction of energy beams arriving at the wall surface is then examined to obtain the shape factor. This method can be efficiently applied to complex geometries. Comparing the rate of convergence and the cost of computing time shows that the shape factor obtained by the present method is better than that obtained by the Monte Carlo method. The influence of the geometric configuration on the accuracy of the shape factor is also investigated. The shape factor obtained by this method is modified by using the original shape factor as a weighting factor. An iteration procedure is developed. The resulting shape factors satisfy the reciprocity law and energy conservation law and the degree of closeness to the exact shape factors is found to be better.