中文摘要：

为了解闪电先导传输的过程以及雷电灾害产生的机理,利用高速摄像观测自然闪电的资料,结合地面电场变化观测,分析了27次自然负地闪先导-回击发展过程的特征。结果表明：〉90%的负地闪首次回击前下行梯级先导具有明显的多级分叉现象,随其下行发展,接近地面时分叉逐渐增多,先导的发展速度为10^4～10^5m/s量级;约30%（8/27）的地闪具有多个接地点;约44%（12/27）的地闪具有多次回击,其中回击次数最大值为13,回击次数〉10的地闪有4次;多接地闪电中有62%（5/8）具有多次回击,但发生多次回击的接地点均只有1个,其余的接地点均只发生1次回击。

英文摘要：

The characteristics of leader-return stroke processes including 27 natural negative cloud-to-ground （CG） lightning discharges were analyzed by using the data obtained by high speed cameras and combining the records of electric field changes produced by lightning on the ground. The results indicates that 90% of stepped leader just before first return stroke present significant branches, and the amounts of branches increase with the development downward of leaders. The speed of stepped leaders is of the magnitude of 10^4 -10^5 m/s. Around 30% （3/27） of lightning discharges produce more than one contact ground point. About 44% （12/27） produce multiple return strokes, and the maximum number of return stroke is 13. There were 4 lightning discharges with more than 10 return strokes. 62% （5/8） with multiple contact ground points produce more than one return strokes. All of those subsequent return strokes have a same ground point in each flash, while each of other ground points is only struck once.