Abstract: In order to improve the stability of surrounding rock and the security of supporting system in deep mine roadways, the directional dilling L type borehole for the ground pre-grouting reinforcement was proposed. The key technologies inclued drilling L type borehole technology, sealing technology of horizontal drilling, matc hing new reinforcing grout liquid and so on. The drilling equipment, inclinometer directional equipment and quality control of drilling mud with L type borehole technolog y were detailedly introduced. The central pumping station and electric power station of Xinhu Mine shaft bottom were grouted. The distance of horizontal grouting reinfo rcement achieved 200m when vertical depth was 999 m. The results showed that the range of single-hole grouting and grouting effect on the basis of a small amount of the number of ground pre-grouting holes was substantially increased. The grouting volume reached 1 459 m3in building up section, grouting volume reached 955. 5 m3i n horizontal drilling section. The stability of surrounding rock of deep mine roadways could be ensured.