Abstract: The RFPA (Rock Failure Process Analysis) code is used to carry out the numerical test using ring specimen as a medium to determine the indirect tensile strength of rock. The effect of diameter of internal hole on failure modes and determined strength of rock specimens is discussed, and the related rock failure mechanisms are clarified. The existing practical problem found in the lab test is also explained according to numerical results. Compared with the test results, both the failure modes and peak loads show in good conformity. Moreover, based on numerical result, a new test scheme is proposed using the cracking load to determine the indirect tensile strength of rock.