Abstract: Based on the cloud-to-ground (CG) lightning location data, weather radar data, satellite data and radiosonde data of Guangdong Province, this paper analyzes the lightning activity of a squall line process in Guangdong Province on 31 March 2014. This paper focuses on the analysis of the variation characteristics of the CG activity in the squall line process and the relationship between the CG activity and the meteorological observation data in the same period. The results show that: in the early stage of squall line development, the CG activity increases rapidly; in the vigorous stage, the CG frequency maintains a high level; in the weakened stage, the CG activity decreases obviously. In the whole squall line development process, the negative CG activity takes the dominant position, and the peak value of positive lightning ratio is about 1h behind the peak value of CG frequency; 92.8% of the CG activity per unit area of squall line process occurred in the echo area with combined reflectivity greater than 40 dBz, and the echo area with combined reflectivity greater than 60 dBz was the most active; In the strong stage of squall line, there are obvious “bow echo”, fuzzy velocity and obvious velocity convergence on radar image; TBB bright temperature lower than 220 K area has a good corresponding relationship with the dense area of lightning activity; the active period of ground lightning activity is usually accompanied by obvious unstable stratification characteristics, mainly including the “upper dry and lower wet” type and the “wet layer deep” type, and there is strong vertical wind shear in the middle and low altitude during the vigorous development stage of squall line.