Purpose. Establishment of laws of change and distribution of the rock mass displacements and deformations on the basis of surveying instrumental observations at undermining the main roadway in the conditions of flat coal seams development in Western Donbas. Methodology. The underground observation station is laid to establish the nature of the spatial displacement of rock mass points in the 2nd West Main haulage drift of c5 layer at "Heroiv Kosmosu" Mine, Industrial Structure Unit. The drift was undermined by clearing works at lava 128 of c1 layer with a thickness of 1,2 m. Processing depth was 80 m. The observations were made using the electronic tachymeter "TOPCON 235N" at 13 metering sections, laid at a distance of about 20 m from each other. Each section at the support is fixed with four survey points: in the walls of mine working, in its roof and the soil. The total length of the observation station was 280 m. The last observation was carried out at a distance of 165 m from lava 128 coal face. To fix mutual displacement of the mine working support and the rock mass, three additional auxiliary metering sections, which consisted of a pair wall ranging marks, were laid. In total there were 4 series of observations at different distances from the face of lava 128. The diagonal arrangement of the main haulage drift with respect to the face line allowed the capture spatial displacement of the rock mass at different distances from the working face. The spatial coordinates of the survey points were determined for each series of the observations. Findings. According to the results of instrumental studies, the spatial coordinates of the survey points are established for each section. To eliminate the impact of convergence on results, the analysis of observations was carried out not according to the survey points, but regarding the center of gravity of the survey section. Uplift of survey points was recorded during the second observation. Thus, the uplift was recorded both in the soil and in the top of the mine working. The maximum value of lifting of the section gravity center was 30 mm. According to the results of studies it is found that rock mass has shifted to the horizontal plane in the direction of movement of the working face after the passage of lava. The maximum value of horizontal displacement of the section gravity center is fixed above the center of the lava and is 240 mm, which coincides with the results of instrumental observations on the Earth surface. The sizes of the propagation zone of rock mass displacement and deformation above the boundary part of the lava were established. Originality. For the first time the regularities of spatial displacement of undermining rock mass above the current lava in conditions of the flat coal seams development are established. Practical value. The research results in their subsequent accumulation provide an opportunity to develop a method for predicting displacement of rock mass above the excavation mine workings of coal mines.