Abstract: The authors have made experiments of turbulent flow (fully developed turbulent flow) velocity distribution of finite rod bundle passages in a square coat (65 x 65mm)in a low pressure horizontal hydraulic loop. Measurement of local velocity lines of centrical unit passage in finite rod bundle center of s/d=1.63 has been taken. There have two passages: as squareness and triangularity Experiment result has been comparied with cal culating of Deissler-Taylor method. Centrical velocity of each centrical unit passage in finite rod bundle passages of three square arrays(s/d=1.28, 1.33, 1.63;s"=31,1.63.6mm) and velocity between farthest rod side and coat inside have also been measured,Measured local velocity entirely uses picot tube made stainless steel injector for O.D.=0.5mm(I.D.=0.25mm).