A new method is given in this paper in order to evaluate the air-to-air missile (AAM) infrared countermeasures (IRCM) performance, the method can be used in detecting IR missile in the assessment phase. By using this method, IRCM tests are analyzed and programmed first, then each missile IRCM test is decomposed into seeker IRCM test and guide & control (G&C) IRCM test in order to measure test data accurately. The resource categories of seeker IRCM test include digital simulation (DSM), hard-in-loop simulation (HTIL), installed systems (ITLS) test and launch test, the resource categories of G&C IRCM test include DSM, HTIL and launch test. By hierarchical Bayesian analysis method the seeker IRCM probability model and the G&C IRCM probability model are deduced, then by Second-moment-equivalent assessment of serial reliability the missile IRCM probability is got. In comparison with the traditional evaluation method, the method discussed in this paper is reliable and precise, and by using it the confidence interval of the AAM IRCM probability can be obtained.