The development tendency of formula of the method of water inrush coefficients was pointed out by combining with the current practice of mining.Taking well field of CIXI for example,the limitation of water inrush coefficients for evaluating risk of floor water inrush in deep mining was proved.Other methods can be a supplement for evaluating water inrush coefficients for evaluating risk of floor water inrush in deep mining.The achieved results can be provided for evaluating water inrush risk of floor in deep mining of some mining areas,in which the water-enriched properties of aquifer are not obvious but water inrush coefficient is larger.