Abstract: This paper used the FLAC^3D to build a model of isolated coal pillar. Through the FISH programming language, the paper obtained the coal and rock elastic strain energy density, studied the accumulation and distribution of isolated coal pillar rock elastic strain energy density, and established the energy density criterion about rockburst hazard. Then the paper made analysis about the variation of coal and rock elastic strain energy density and energy density factor under the affection of working face depth, roof and floor elastic modulus, coal pillar width and other related factors.