Abstract: Pre-grouting reinforcement of the current coal floor with directional borehole is an important innovation of coal floor water prevention，combined directional drilling with floor pre-grouting reinforcement. This paper systematically studied on pre-grouting reinforcement principle，drilling equipment，drilling designing，and drilling technology，and a set of directional drilling technology and equipment for coal floor pre-grouting reinforcement is formed. The experiments in Zhaogu mine No.11151 work face show that the drilling technology and equipment above is reliable and advanced，and the effect of floor grouting reinforcement is good. The research enriches and improves the coal floor water prevention methods，achieving a major breakthrough in advance prevention of disasters resulted from ground water. It is significant for the safe and efficient exploitation of coal mine.

Key words: Coal floor water prevention, Directional borehole, Drilling technology, Drilling equipment, Pre-grouting reinforcement