Abstract: The reliability assessment of the unit-system is the most important content in the reliability assessment of complex systems. The general calculation formulae of the entropy method synthesis on the systems consisting of identical success-failure binomial units are derived by use of the addible characteristics of information quantity and the principle of equal information quantity. The general model of the entropy approximate lower limits for the system reliability is gave according to the fundamental method of the unit reliability assessment. The application of the assessment method is analyzed by way of examples. The assessment results are very satisfactory. The assessment method proposed can be popularized to the systems which have a fixed reliability structural model.

Key words: Entropy Success-failure model unit, Information quantity, Reliability assessment