Because　of　the　nonlinearity　nature　of　contacts,　real　contact　information　in　discontinuous　computation　is　unknown　before　analysis.　In　standard　three-dimensional　(3D)　discontinuous　deformation　analysis　(3D　DDA),　the　indeterminacies　of　the　contacts　arise　from　two　aspects:　the　singular　block　boundaries　and　the　nonsmooth　frictional　behavior.　Because　the　contact　occurs　only　at　the　first　entrance　position,　the　first　entrance　theory　is　the　general　physical　law　of　block　contacts.　Therefore,　the　first　entrance　approach　is　proposed　in　this　study　to　select　the　first　entrance　plane　and　to　evaluate　the　related　first　entrance　points,　along　which　the　contact　forces　would　be　applied.　Furthermore,　the　procedure　and　criteria　of　the　open-close　iteration　(OCI)　for　the　3D　frictional　contact　problem　is　presented　to　determine　the　most　suitable　status　and　force　of　each　contact.　With　this　rigorous　method,　the　information　of　each　contact　can　be　determined,　such　that　the　two　kinds　of　the　contact　indeterminacies　are　resolved.　The　effectiveness　of　the　proposed　method　is　verified　by　three　numerical　tests,　suggesting　that　the　proposed　method　works　at　a　practical　level　in　accuracy　and　robustness.　(c)　2018　American　Society　of　Civil　Engineers.