Abstract:With reference to the method suggested by ISRM for determining the fracture toughness of rock,quasi-static fracture toughness of anthracite has been measured on the Instron 1342 electro-hydraulic servo controlling material testing machine for the first time using short rod specimens. The fracture toughness value increases fast when displacement rate is lower,but trends to be steady when the rate is higher. The reason for load jump when specimen is fractured has been analyzed on the basis of P-COD curves,and the time when the triangular ligament starts fracturing can be known according to load jump. The result indicates that the influence of geometrical error on the fracture toughness values of anthracite is small and the error is less than 2.4%;but the influence of geometrical error on the elastic modulus is large and the error reaches to 13.3%. Meanwhile,the degree of non-linearity of anthracite has been evaluated according to the graphical construction method,and it is larger than 0.4.