The lightning current amplitude and gradient are significant in the fundamental researches of lightning protection and science. A statistical analysis is made of 729598 lightning flashes monitored by the ADTD lightning location system in Chongqing between 2006 and 2008, with focus on the analysis of the distribution characteristics of lightning current gradient and frequency. The results show that the lightning wavehead gradient and frequency are different with different polarities; the gradient of positive lightning is obviously greater than that of negative lightning, and the frequency of negative lightning is obviously greater than that of positive lightning at the same gradient; the correlation coefficient between lightning current amplitude and gradient is +0.613; there is great difference between the probabilitydistribution characteristics, as well as the statistical characteristics, of the lightning gradients calculated by the DL/T620recommended wavehead time and that calculated by the CIGERrecommended formula. Based on these findings, the limitations of lightning current gradient obtained by the ADTD system are analyzed, which offers theoretical evidences for the right selection of lightning gradient parameters.