:Objective To explore foranatomic basis and improve drainage effects on CLCFD.Methods The MR machine of SiemensTrio Tim 3.0 T was used to scan the normal spinal canal of 64 adult subjects.The datum wasmeasured in the median sagittal section of the lumbar vertebral column.Through midpoint oflumbar L3-L4 and L4-L5 vertebral disc's,we painted vertical lines of vertebra,named H1 andH2 lines.The vertical line cross vertebral column at two points.The midpoint of two pointsis measured point(A is L3-L4,B is L4-L5).We measured distance from the junction of H1 orH2 lines and skin S1 or S1 to subarachnoid space,distance from A or B to the ending ofspinal and dural pocket.Results The distance from S1 or S1 to subarachnoid space was (51.3±7.4)mm,(53.3 ±8.4)mm.A,B point to the ending of spinal were(90.1 ±16.4)mm,(121.9 ±17.3)mm.A,Bpoint to the ending of dural pocket was(91.1 ±14.4)mm,(61.6 ±13.0)mm.The distance fromA,B point to the ending of spinal and B point to the ending of spinal and dural pocketwere statistically significance(P<0.01).Conclusion Select lumbar L4-L5 puncture and cephaladimplant catheter at first.It is possible to implant catheter cephalad or cauda if selectlumbar L3-L4 puncture,but cephalad implant catheter is beneficial to the cerebrospinalfluid drainage. Key words: Magnetic resonance imaging; Lumbar vertebral space; Lumbarcerebrospinal fluid drainage