In order to improve the performance of the Generalized Cross Correlation (GCC) method for time delay estimation, a new arithmetic which combined with GCC and Second Correlation has been proposed. The main process of the new arithmetic is as the GCC method except that the signals are auto-correlated and inter-correlated before the weighting processing. Simulation tests indicated that its performance of anti-interference and precision is better than GCC. To verify the proposed method, the artificially triggered lightning data was processed, which proved the new arithmetic could be competent to the lightning radiation source location and increase the location accuracy effectively.