Taking　the　granite　specimen　with　multiple　fissures　as　the　main　research　object,　the　mechanical　response　and　failure　mechanism　of　the　granite　specimen　under　uniaxial　compression　tests　were　analyzed　by　constructing　a　numerical　analysis　model　based　on　cohesive　element　and　Voronoi　polygons　techniques.　Furthermore,　the　effects　of　geometric　characteristics　(spacing,　length,　width)　on　the　peak　mechanical　response,　damage　energy,　number　and　proportion　of　micro-cracks,　failure　mode　and　so　on　are　further　studied.　The　results　show　that　the　numerical　analysis　model　can　accurately　reproduce　the　complex　intergranular　occlusion　and　multi　fissures　network　structure　of　granite　specimens,　and　reveal　the　dominant　role　of　fissure　angle　on　the　failure　mode,　and　the　significant　influence　of　fissure　geometric　characteristics　on　the　number　and　proportion　of　micro-cracks,　peak　mechanical　response　and　damage　energy.　The　crack　path　and　failure　mode　are　significantly　affected　by　the　change　of　fissure　angle　and　spacing,　while　the　increase　of　fissure　length　and　width　leads　to　more　rapid　failure　and　lower　peak　mechanical　response.　The　damage　energy　increases　gradually　with　the　increase　of　fissure　spacing,　but　decreases　with　the　increase　of　fissure　length　and　width.　This　study　not　only　deepens　the　understanding　of　the　mechanical　behavior　of　granite　samples　under　complex　geological　environments,　but　also　provides　theoretical　support　for　accurate　assessment　and　effective　reinforcement　of　rock　mass　stability　in　engineering　practice.　©　The　Author(s)　2025.