Abstract: The quantified evaluation of reducing power grid losses needs to compare the grid losses between pre-and post-implementation of the measures to reduce the grid losses in a specified cycle. However, when those measures are performed, it can hardly determine the grid losses without those measures, i.e., the baseline of reducing losses. Therefore, an enhanced method to improve the accuracy of the baseline is required for the quantified evaluation of reducing losses. According to the IPMVP definition of the baseline, firstly the accuracies of the Markov Chain（MC） and exponentialsmoothing-based methods were improved in obtaining the vertical and horizontal baselines of reducing losses. Then, parameters in the two improved methods were matched, and calculation results were combined with different weight factors to form a final loss reduction baseline considering both vertical and horizontal orientations. Hence, the final baseline complements the regular difference between the vertical and horizontal data and enhances the precise of the proposed methods. The numerical studies show that the proposed method exhibits a remarkable reduction of errors in determining the baseline of reducing losses during the specified cycle.