Abstract: Five typical influence factors were selected， including diameter of tunnel， buried depth， strata inclination， thickness ratio of slate to sandstone and side pressure coefficient. By adopting the orthogonal tests， the influence rules of these different factors to surrounding rock stability were obtained by 3DEC numerical simulation software. The results showed that: side pressure coefficient was the most significant factor of affecting surrounding rock stability， as the strata inclination was the least； With the diameter of tunnel increasing， the maximum stress and maximum displacement of linear also increases. When the diameter of tunnel was more than 9 m， the influence on maximum displacement became larger； When buried depth was ranging from 500 m to 700 m， the influence of buried depth on maximum displacement and maximum stress was the largest； The displacement and stress of linear showed a decreasing trend with the ratio of slate to sandstone increasing；（4）When side pressure coefficient was at 1.0， the maximum stress and maximum displacement was the least. When side pressure coefficient was more than 1.5， the maximum stress and maximum displacement raised sharply with side pressure coefficient increasing.

Key words: Orthogonal test, Numerical simulation, Deep tunnel, Surrounding rock stability, Influence factors