Nuclear　energy　with　attractive　expectation　can　be　efficiently　used　by　the　supercritical　carbon　dioxide　power　system.　However,　amounts　of　the　cooling　heat　is　wasted　in　the　nuclear　power　plant.　Two　conceptual　designs　of　combined　heat　and　power　systems　based　on　the　supercritical　carbon　dioxide　power　system　are　proposed　to　exploit　the　waste　heat.　A　comparison　research　is　performed　in　thermodynamics　and　economics.　Several　key　physical　parameters　are　selected　to　investigate　their　effects　on　system　performance,　and　multi-objective　optimization　using　the　Non-dominated　Sorting　Genetic　Algorithms-II　is　carried　out　with　the　target　of　gaining　maximum　system　exergy　efficiency　and　minimum　total　product　unit　cost.　The　results　of　parameter　analysis　exhibit　that　there　exist　optimal　values　for　two　target　functions　with　the　increasing　compressor　pressure　ratio　for　three　thermal　systems,　and　the　system　with　heat　pump　needs　the　highest　pressure　ratio.　Better　system　performance　can　be　achieved　by　increasing　the　turbine　inlet　temperature　and　evaporator　temperature.　The　multi　objective　optimization　results　of　genetic　algorithm　display　that　proposed　two　systems　can　gain　an　improvement　by　7.02%　and　8.45%　for　the　system　exergy　efficiency,　and　11.95%　and　13.48%　for　the　total　product　unit　cost　compared　with　the　stand-alone　supercritical　carbon　dioxide　system,　respectively.