The in-situ stress measurements of 12 pits have been conducted within the depths of from -500 to -1 000 m in Huainan Coal Mine by using hydraulic fracturing technique and stress relief method by overcoring; and the measurement data of 19 effective measuring points have been obtained. The analyses of the measurement data indicate that: (1) The in-situ stress field in Huainan Coal Mine

in which the tectonic stress takes absolute predominance

is dominated by horizontal stress and belongs to typical tectonic stress field. (2) The magnitudes of the in-situ stresses are high stress level. (3) Vertical principal stress

maximum and minor horizontal principal stresses all show increasing trend with the increase of depth. (4) The ratio of maximum horizontal principal stress to vertical principal stress

decreases with the increase of depth; the in-situ stress field has the changing tendency from dynamic to static. (5) The regression curve for the ratio of average horizontal principal stress to vertical principal stress

distributes between the maximum and minimum envelopes of Hoek-Brown curve; and its change trend is similar with the Hoek-Brown curve

but compared with the Hoek-Brown’curve

the value of the regression curve is smaller. (6) The ratio of maximum to minimum horizontal principal stress ranges from 1.12 to 2.02

in which 68.42% of measuring points ranges from 1.67 to 2.02. (7) The orientation of maximum horizontal principal stress is about NEE-EW. At last

the relationship between in-situ stress and tectonics for Huainan mining area is discussed. The analysis suggests that the orientation of maximum principal stress is closely related with the tectonic movement

while the orientation of current tectonic stress field is roughly identical with that of the measured maximum horizontal principal stress of mining area.