The　reliability　evaluation　of　generation　systems　is　an　important　part　of　that　of　power　systems.　The　reliability　indices　of　generation　systems　are　first　discussed.　Then　this　paper　proposes　a　concept　for　reliability　evaluation　of　generation　systems　based　on　the　probabilistic　production　simulation　method　taking　the　load　capacity　constraint　and　the　energy　constraint　into　account.　Based　on　the　concept,　a　software　package　REGEN　is　developed.　This　paper　details　its　functions,　features　and　design　steps.　Its　application　on　a　real　power　system　is　given　to　demonstrate　the　effectiveness　of　the　proposed　method.