Abstract: To explain the reason for the abruptly thin thickness of coal in Hole T4, 3D exploration technology is used in loess region firstly. After integrated interpretation of the hole core, well-logging and 3D data, it is found out why the variation of coal thickness in Hole T4 and the trend of coal thickness in this region. According to the validation result, it is proved true of the 3D high precision explanation that the variation of coal thickness is mainly controlled by the ancient sedimentary environment. The result is very important for the partition of mining work face, planning of gallery and security production.