By means of the small borehole hydraulic fracturing measurement unit designed for underground coal mines, in situ stress measurements at 160 sites were made in Jincheng, Lu'an, Fenxi, Huajin, Yangquan, Pingshuo and Datong coal mining fields in Shanxi province, which cover the most geological conditions of Shanxi coal mines. The relation between in-situ stresses and depths of measurement sites, and the in-situ stress status of different depths were analyzed based on measurement data. The underground in-situ stress distribution map of Shanxi coal mining fields was drawn and the characteristics and law of underground in situ stress distribution was made by comparing the results with the focal mechanism solutions. It is shown that the horizontal stresses basically increase with the depths of measurement sites as a whole. A large scatter of the in-situ stress measurements is also found because of the different geological conditions in different coal mining fields. The in-situ stress patterns are σ_Hσ_σ_h when depth is below 250 m, σ_Hσ_vσ_h when depth is between 250 m and 500 m, and σ_vσ_Hσ_h when depth is above 500 m. The ratio between the maximum horizontal principal stresses and vertical principal stresses mostly concentrates in the interval of 0.5 to 2.0, and decreases and converges to 1 with the depth increasing; The ratio between the maximum horizontal principal stresses and minimum horizontal principal stresses is mainly in the interval of 1.5 to 2.0; The ratio between the mean horizontal principal stresses and vertical principal stresses mainly varies from 0. 5 to 1. 5 with most in the interval of 0.5 to 1.0. The orientations of the maximum horizontal principal stresses in Shanxi coal mining fields change considerably from north to south. The orientations are NE in northern part, deflect to NNW southwards, vary to NW in western and eastern parts, and changeable in southeast part. Comparing the results from underground in-situ measurements with the focal mechanism solutions, they show good agreement in some coal mining fields, but obvious divergence exists in other areas. Especially in the areas affected by local large geological struetures, the orientations of the horizontal principal stresses frequently reverse and change obviously.