In　lumbar　anesthesia　surgery,　the　accurate　determination　of　key　parameters　such　as　injection　angle　and　dosage　is　facilitated　by　the　real-time　observation　of　intrathecal　drug　distribution.　In　this　study,　a　non-invasive　and　visual　computational　fluid　dynamics　method　was　used　to　simulate　drug　injections　in　the　\cloverleaf　＂　lumbar　thoracic　segment　with　a　multiphase　mixture　model,　clarifying　the　intrathecal　unsteady　flow　behaviors　and　the　drug　transport　mechanisms.　The　transport　properties　of　three　clinically　significant　injection　angles　-　0̊,　45̊　and　60̊-　were　compared,　determining　the　fastest　and　slowest　block　onset　angles　based　on　drug　concentration　levels　in　the　thoracic　vertebral　plane.　The　calculation　results　are　aligned　with　clinical　practice　trends,　and　it　is　found　that　significantly　different　drug　amounts　are　required　for　different　injection　angles,　with　higher　doses　necessitated　for　ultrasound-assisted　anesthesia.　During　anesthesia,　a　trend　of　increasing　and　then　decreasing　local　anesthetic　concentrations　in　each　vertebral　plane　was　observed,　with　the　presence　of　a　minimum　effective　dose　of　local　anesthetic　at　the　target　block　site.　Injecting　at　the　\concave＂　part　of　the　cloverleaf　(45̊　and　60̊)　results　in　greater　drug　pulsation,　faster　diffusion　and　more　efficient　mixing　than　injecting　at　the　positive　\convex＂　part　of　the　cloverleaf　cross-section　(0̊).　At　the　L2　vertebral　plane,　the　flow　rate　and　mixing　ratios　during　injection　for　angles　of　0̊,　45̊　and　60̊　were　approximately　1:4:2.　Compared　with　orthostatic　0̊　injections,　45̊　and　60̊　oblique　injections　resulted　in　higher　drug　concentrations　in　the　T12-10　vertebral　plane　during　the　pre-transport　period,　with　45̊　injections　being　the　fastest.　However,　over　a　longer　period　of　time,　45̊　injections　resulted　in　the　lowest　drug　concentrations　in　the　target　block　plane　(T10),　necessitating　a　higher　dose.　A　faster　anesthetic　response　was　produced　by　0̊　injections　at　the　same　dose.　Valuable　insights　for　the　application　of　appropriate　drug　dosages　in　clinical　anesthesia　practice　are　offered　by　the　calculations.　©　World　Scientific　Publishing　Company.