Abstract: The deformation and failure behavior of brittle rock in uniaxial compression were analyzed to establish a theoretical constitutive damage model based on damage mechanics. The numerical and experimental tests for brittle rock specimens (coal specimens included) in uniaxial compression were also carried out to obtain the complete stress-stain curves of the rocks using numerical testing machine(RFPA) and servo-controlled testing machine (RMT-150B), respectively. Based on the theoretical, numerical and experimental results,the relations and differences of complete stress-strain curves were contrastively investigated. It is concluded that numerical simulation is not a simple duplication for analytical method but an effective method to investigate the complete process of rock deformation and failure.