The characteristics and amount of charge transferred by negative cloud-to-ground (CG) lightning have not only become an important research field with respect to the mechanisms of lightning discharge, but also have important practical applications for lightning protection. In order to study the lightning discharge characteristics and intensity in the Beijing region over a typical urban surface environment, using the slow and fast antenna synchronized by GPS (Global Position System), quantitative observation data were obtained and analyzed to study the characteristics of negative return strokes. After eliminating the effect of the observation site and environmental factors on the electric field change as much as possible, the magnitude and locations of charge sources neutralized by strokes were fitted by using a Monte Carlo data processing method and nonlinear least-squares fitting algorithm. In addition, the relations between the stroke characteristics and the charge magnitude and locations were also studied. The results were as follows: (1) The charge lowered by a discrete negative return stroke ranged from 1.1 to 27.6 C with an arithmetic mean of 8.6 ±5.2 C. The minimum of the stroke charge did not change significantly with the stroke order, while the maximum and the arithmetic mean of the stroke charge increased with the stroke order. The total charge lowered to the ground by a single negative flash increased with the number of strokes it contained. (2) The percentage of multi-stroke negative CG lightning flashes was 70.4%, and the stroke number and the interstroke interval both fitted a lognormal distribution. The interstroke interval ranged from 3 to 967 ms with an arithmetic mean of 99 ±95 ms. The minimum of the interstroke interval did not change significantly with the stroke order either, while the maximum and the arithmetic mean of the interstroke interval also increased with the stroke order. (3) The average charge lowered by a discrete stroke increased with the interstroke interval preceding it, and the average distance between the adjacent stroke sources showed a similar trend.