Abstract: This paper analyses factore affecting ‘the fourth below’ up-growth and calculates some hydrogeological parameters.Taking Qidong Mine as a example,based on the data about the water inrush from the fourth aquifer, the parameters are revised, which are calculated by pumping test. The result is applied in adjacent coal mine. Through above research, in the old river channel where water-abundance is good, the pillar must be suitably left for the safe of mining.