Abstract: The high shear rate flow (1215~23120\,s^-1)characteristics of the partically hydrolyzed polyacrylamide (HPAM) insilica micro-tubes with diameters in the range of 10.1~325\mumwere investigated experimentally. It is shown that the effect of themicrotule is obvious in microtubes with diameters less than 100\mum.The experimental averagevelocity is higher than expected which is the flow of the same solution ingeneral-sized tubes. In addition, the discrepancy between the experimentaland the expected average velocities is influenced by the diameter andthe shear rate. Under the same shear rate the smaller the diameter ofthe microtube is, the more obvious the discrepancy is. In microtubes thediscrepancy decreases as the shear rate, however, if the diametersbeyond 30.7\mum, the discrepancy hardly varies with the shear rateany more.