Abstract: According to surface subsidence basic characteristics of steep coal seam and probability integral method, the steep seam mining unit is simplified upright seam mining. Based on the Euler's constant, the article puts forward a kind of logarithm method for steep seam mining (seam inclination > 75°) maximum subsidence calculation. The formula is practical and the parameter is stability. The method was verified by field data form Kongji Mine, example proves that this method is scientific. The method can be used for predicting ground subsidence after steep coal seam mining.