Abstract: In order to determine reasonable lag safety distance of shallow buried 1-1 coal and 2-2 coal in Longde mine, CT detection technology and borehole stress monitoring system are used to carry out the measured study on the simultaneous mining stress distribution of upper and lower coal seams. Study concludes that CT detection determines that the leading mining stress range of 2-2 coal seam for fully mechanized large cutting height face is 59.5m, and roof of 1-1 coal seam began to collapse is about 47.5m behind the goaf, and affect the stress distribution of 2-2 coal seam below. The borehole stress gauge has determined that the maximum distance affected by the leading stress on 2-2 coal seam is 50.7m, the stress peak is 6m ahead of working face, and stress concentration coefficient is 1.23, but working face of 2-2 coal seam are not affected by the adjacent working face with 20m coal pillar and the overlying coal mining with an interval of 54m roof layer thickness. Three calculation methods are used to determine that the reasonable lag distance of upper and lower coal seams co-mining in Longde mine is 138.4m. The numerical simulation study shows that the tensile stress runs through the whole interval within 50m, thus verifying the safety of the coordinated safe interval of 138.4m between upper and lower coal seams in Longde coal mine.