In order to find a way to study the structure reliability further, the basic system of structural and the methods of analyzing were introduced. For the series system and parallel system, the calculation can be categorized into Point estimated method and interval estimated method. The point estimated method includes Stevenson-Moses method, Probability Network Evaluation Technique, Conditional Probability Method and Integrated Correlation Coefficient Method. The interval estimated method includes General boundaries of range and the narrow boundaries of range. The principle of method and the calculation steps methods were depicted in detail. This study has significance in theory and practice for the study of structural reliability.