Abstract: The Chengdu Plain is located in the warm and humid subtropical climate zone influenced by the southeast Pacific monsoon, featuring highly active meso-and microscale weather systems and frequent lightning activities.For the analysis and application of ADTD（advanced direction and time-of-arrival detecting system, ADTD）lightning monitoring data, it is essential to perform quality selection on lightning data.Based on the lightning monitoring data from 2011 to 2020 in the Chengdu area, this study analyzes the time distribution characteristics of low-amplitude lightning.The log-normal fitting analysis method, The log-normal fitting analysis method determines that the interference range of low-amplitude ground flashes in Chengdu′s lightning monitoring data is an absolute value of ≤ 3.10kA.Log-normal fitting tests show that the fitting effect is better after excluding this part of lightning data.The findings indicate that the log-normal analysis method can quantitatively identify the interference interval within low-amplitude lightning data in Chengdu, thus providing a theoretical basis for lightning data processing and application in this area.