This　study　presents　a　hydromechanical　model,　finite-discrete　element　method　with　fluid　flow　in　three　dimensions　(FDEM-flow3D),　that　can　simulate　three-dimensional　hydraulic　fracturing　of　jointed　rock　mass　with　complex　fracture　networks.　By　taking　full　advantage　of　a　unique　topological　connection　between　joint　elements　and　solid　elements　in　three-dimensional　combined　finite-discrete　element　method　(FEMDEM)　together　with　the　cubic　law,　the　authors　built　a　three-dimensional　fluid　flow　model.　In　addition,　a　connectivity　search　algorithm　for　arbitrarily　complex　three-dimensional　fracture　networks　is　proposed,　which　can　be　used　to　search　the　connectivity　of　arbitrarily　complex　three-dimensional　fracture　networks.　Combining　the　connectivity　search　algorithm　and　the　mechanical　calculations　of　three-dimensional　FEMDEM,　the　authors　built　the　three-dimensional　hydromechanical　coupling　model　FDEM-flow3D,　which　directly　implements　hydromechanical　coupling　and　can　simulate　fluid-driven　fracturing　in　rock　with　arbitrarily　complex　three-dimensional　fracture　networks.　Finally,　the　authors　give　five　examples　to　validate　FDEM-flow3D　in　dealing　with　the　problems　of　steady　flow,　unsteady　flow,　hydromechanical　coupling,　connectivity　search　of　discrete　fracture　networks,　and　hydraulic　fracturing.　The　simulation　results　agree　well　with　the　theoretical　or　experimental　results.　The　model　provides　a　powerful　tool　for　simulation　of　hydraulic　fracturing　in　shale　gas　exploitation　and　geothermal　extraction.