AnewmethodforsimulatingthefoldingpathwayofRNAsecondarystructureusingthemodifiedantcolonyalgorithmisproposed.ForagivenRNAsequence,thesetofallpossiblestemsisobtainedandtheenergyofeachstemiscalculatedandstoredattheinitialstage.Furthermore,amorerealisticformulaisusedtocomputetheenergyofmulti-branchloopinthefollowingiteration.Thenafoldingpathwayissimulated,includingsuchprocessesasconstructionoftheheuristicinformation,theruleofinitializingthepheromone,themechanismofchoosingtheinitialandnextstemandthestrategyofupdatingthepheromonebetweentwodifferentstems.FinallybytestingRNAsequenceswithknownsecondarystructuresfromthepublicdatabases,weanalyzetheexperimentaldatatoselectappropriatevaluesforparameters.ThemeasureindexesshowthatourprocedureismoreconsistentwithphylogeneticallyprovenstructuresthansoftwareRNAstructuresometimesandmoreeffectivethanthestandardGeneticAlgorithm.