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This paper introduces a new thunderstorm identification algorithm called combinatorial 8‐connectivity method based on total lightning activity as observed by the Foshan total lightning location system. The influence of spatio‐temporal parameters on the outcome is presented. The evaluation method contains four criteria: the fitting area of lightning clusters, the area proportion of lightning clusters, the number of lightning clusters and the utilization rate of lightning events. It is found that the fitting area adopting grid cells with size 0.02°–0.05° remains constant around 4, 9, 16 and 25 times those using grid cells of 0.01° in size, respectively. The evaluation criteria change by less than 0.61 km2/min in area, less than 0.43%/min in area proportion, less than 1/min in number and less than 2.8% in utilization rate using 0.01° grid cell when the duration of time interval exceeds 6 min and the spatial gap between grid cells with lightning events is more than 2 gaps. Then, the evaluation results of the combined 8‐connectivity method are compared with the results of the connected‐component labeling method (8, 24, 48, 80 and 120‐connectivity method), and it is found that the performance of combined 8‐connectivity method is better to outline lightning cluster. The two methods have been applied to case analysis on 15 May 2014. Key Points: Due to the random distribution of total lightning data, a thunderstorm identification algorithm is introducedAn identification evaluation method is introduced to analyze the performance of different methodsAccording to the analysis of spatiotemporal parameters, stable spatiotemporal parameters are selected to identify lightning clusters [ABSTRACT FROM AUTHOR]