Evaluating the reliability of a power grid Security and Stability Control System (SSCS) is a necessary prerequisite for its reliability design, and is of great significance for ensuring the safety and stability of the power grid. First, the research status of reliability evaluation indices and reliability evaluation methods for the secondary system of a power grid are reviewed. The reliability evaluation indices are examined from aspects of time and probability. Four analysis methods which can be used to study the reliability of SSCS are summarized. Then, the Markov state space and Monte Carlo methods are used to evaluate the reliability of a typical engineering application of an SSCS. The applicability of the two methods in reliability analysis of small-scale SSCS is compared, and the mathematical expressions of failure rate, repair rate and system availability are derived. Finally, through the comparison of the advantages and disadvantages of the above two reliability analysis methods, suggestions are made for the further study of the reliability of large-scale complex SSCSs using various reliability analysis methods comprehensively. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 5100-201940006A- 0-0-00) “Research on Intrinsic Safety Improvement Technology of Security and Stability Control System for AC/DC Power Grid”.