Abstract: The wave velocity and tensile of coal samples were systematically been tested and analyzed.The results showed that the wave velocity and tensile strength of coal were obviously anisotropic and had very close relationships.The relation formula of wave velocity-strength were established.The wave velocity of coal seam were tested under mine.According to the test strength in terms of wave velocity and calculated strength based on integrity,the tensile strength of coal mass was determined.It provided not only important parameters for designing reasonable waterproof measures,but also a new method for determining strength of coal seam.