The effect of the mechanical grinding on the structure and mechanical properties such as microhardness of the disperse thermally expanded graphite (TEG) has been studied. A comparison of the parameters of a deep structure of obtained TEG samples by X-ray diffraction method has been provided. The microhardness and elastic characteristics of disperse expanded graphite has been studied by the methods of continuous nanoidentation. It was shown that with a decrease in the average particle size, the branched morphology of TEG particles changes and the shape approaches to the equiaxial. It was determined that particles of thermally expanded graphite with an average particles cross-section of 120 μm have maximum microstresses, and the compactated samples are characterized by the maximum values of microhardness and Young's modulus, that is 0.12 GPa and 1 GPa respectively. The criteria of the powder mixtures treatment for disperse TEG powder, predicted changes in particles morphology and mechanical characteristics of the compacted samples obtained have been optimized.