The　study　of　the　rock　crack　propagation　and　fracture　behaviors　during　impact　fragmentation　is　important　and　necessary　for　disaster　evaluation　of　rockfalls.　Discontinuous　Deformation　Analysis　(DDA)　incorporating　virtual　joints　can　offer　a　powerful　tool　to　solve　such　a　problem.　In　the　analysis　process,　the　computational　efficiency　is　critical　because　the　mesh　must　be　very　dense　to　make　crack　propagation　more　realistic.　Thus,　parallel　DDA　using　OpenMP　is　applied.　The　flattened　and　precrack　Brazilian　disc　tests　are　first　reproduced,　respectively,　to　verify　the　accuracy　and　efficiency　of　the　parallel　DDA　with　virtual　joints.　Then,　the　impact　fragmentation　process　is　simulated　and　validated　with　corresponding　laboratory　experiments　in　terms　of　crack　propagation　results.　Furthermore,　the　effects　of　joint-slope　angle,　joint　connectivity　rate,　and　impact　velocity　on　rock　fracture　behaviors　are　investigated.　It　is　concluded　that　the　peak　number　of　cracks　occurs　when　the　joint-slope　angle　ranges　between　30　degrees　and　45　degrees;　the　higher　impact　velocity　and　joint　connectivity　rate　tend　to　cause　more　cracks　and　larger　damages　to　the　specimen.