In　practical　engineering,　the　tensile　properties　of　granite　have　garnered　significant　attention.　To　investigate　the　tensile　mechanical　behavior　and　failure　mechanisms　of　granite,　comprehensive　studies　are　essential.　This　study　establishes　a　numerical　model　based　on　three-dimensional　grainbased　models　(3D-GBM)　within　the　discrete　element　method,　considering　the　internal　mineral　grain　structure　of　granite.　The　model　implements　a　multi-level　classification　of　force　chains　and　microcracks.　Quantitative　analysis　was　performed　on　the　tendencies,　quantities,　and　contact　forces　of　multi-level　force　chains　and　microcracks.　The　analysis　examines　the　tensile　strength,　microcrack　distribution　characteristics,　and　grain　size　effects　of　granite　from　the　perspective　of　force　chains.　Results　indicate　that　under　indirect　tensile　loading,　force　chains　form　between　adjacent　particles　with　varying　distribution　tendencies.　High-strength　force　chains　effectively　represent　the　load-bearing　capacity　of　granite,　predominantly　oriented　near　the　loading　direction　and　primarily　located　in　the　center　of　the　sample.　Additionally,　granite　exhibits　a　significant　grain　size　effect;　as　the　size　of　mineral　grains　increases,　the　number　of　intragranular　contacts　with　higher　mechanical　parameters　rises,　leading　to　an　increase　in　high-strength　force　chains　and　microcracks.　Consequently,　higher　external　loads　are　required　to　induce　failure,　resulting　in　increased　tensile　strength.