Abstract：Coulomb strength criterion means that the maximum axial stress of a given specimen increases with confining pressure linearly under the pseudo-triaxial compression. The strength of rock specimen is gotten after its destroy，so one specimen can give the strength under one confining pressure only. Unlike the local flaws in sedimentary，the fissures and weakness in coal are distributive，which influence both deformation and strength. Specimens form various coal blocks are of great difference in mechanics property. The uniaxial strength is 5.3～10.4 MPa and Young¢s modulus is 2.36～3.17 GPa for specimens from Block A，strength 9.8～35.0 MPa and Young¢s modulus 3.08～4.64 GPa for specimens from Block B，strength 5.9～20.7 MPa and Young¢s modulus 2.34～4.55 GPa for specimens from Block E，respectively. The strength and Young¢s modulus of specimens compressed uniaxially are of great dispersion，but there is a good correlation between them. Fissures in coal specimen compressed under confining pressure will close and axial stress is supported by the friction，which results in the decrement of dispersion of strength and Young¢s modulus. The strengths of specimens from different coal blocks are different，but the coefficients of influence of confining pressure on the triaxial strength or the internal friction coefficients are the same for three coal blocks. The internal friction coefficient is a material parameter and the cohesion is a strength property of coal block. So all the strengths of different coal blocks，no matter how many specimens are made，can be regressed jointly，and the strength property of coal blocks can be known as well. The strength criterion can be decided from various blocks.
