Abstract: The risk assessment of water inrush from Ⅱ1 coal floor L8 limestone is analyzed when tunnel excavation and coal mining, based on introducing the formation conditions of Zhaogu No.1coal mine. Pre-grouting is the main means to solve the water inrush from coal seam floor. The underground coal seam floor pre-grouting and water prevention control technology is summarized according to the previous construction experience, which is commonly used now. And at the same time, the ground pre-grouting technology with horizontal directional horizontal hole to control water is introduced, combing with the development of new technology. At last the two kinds of grouting and water prevention control technology are compared and analyzed, their advantages and disadvantages and applicable conditions are described. The results show that the ground pre-grouting technology with horizontal directional horizontal hole to control water is suitable for water prevention and control of coal seam floor, and has achieved good results.