Experimental　studies　indicated　that　most　rocks　exhibit　distinct　elastic　moduli　under　compressive　and　tensile　loading,　leading　to　intricate　stress　conditions　in　rock　mass　under　thermal-mechanical　coupling.　It　is　an　urgent　demand　for　advanced　numerical　methods　that　can　simultaneously　consider　the　bi-modular　elasticity　of　rock,　thermal-mechanical　coupling　effects,　and　thermal　cracking　behaviors　to　improve　understanding　of　geological　science.　The　Balanced　Interface　Method　(BIM),　a　novel　bi-modular　elastic　algorithm　is　proposed　in　Particle　Flow　Code　to　investigate　the　thermal-mechanical　behavior　of　bi-modular　elastic　materials.　Firstly,　this　study　introduces　the　calculation　principle　of　BIM　and　presents　the　calibration　procedure　for　bi-modular　elastic　materials,　which　is　further　validated　through　two　case　exercises.　Subsequently,　the　thermal-mechanical　coupling　algorithm　is　improved　by　utilizing　the　Flat-Joint　Model　(FJM),　and　a　correction　method　for　the　position　of　the　compressiontension　interface　based　on　BIM　for　the　thermal-mechanical　coupling　process　is　introduced,　which　is　then　verified　by　a　comprehensive　transient　heat　conduction　case　with　different　elastic　assumptions.　Lastly,　a　cracking　example　induced　by　thermal-mechanical　coupling　is　simulated.　The　numerical　results　demonstrate　consistency　with　previous　studies　and　reveal　a　significant　improvement　in　the　thermal　cracking　behavior　of　rock,　proving　the　developed　algorithm＇s　necessity　in　investigating　the　coupled　thermal-mechanical　problem.