Abstract: From the analysis of pulsating flow, it is shown that the direct application of flowmeter to the pulsating fluid flow measurements must has two conditions, namely the relocity is proportional to the measured parameter and the reading of the measured parameter is the mean valule of time. To attaining these two conditions, laminar fi_owmeter depends on the laminar element consisting of a number of narrow passages, and the measuring pressure tube with damping element. The choosing of structure tupes of laminar elements, the design method of laminar flowmeter and the process of the laminar elements and disussed in details. The upper limited valules of Reynolds number Re and Re R e·l/d d equivalent diameter, the length of element) are very important paraments for holding the linear relation between the velocity and pressure drop in the measuring range. For establishing the standard characteristic and using the laminar flowmeter more accurately, the formulue (30) and. (31) are necessary.The D-100 laminar flowmeter designed by authors was experimented on the 195, 295 and 395 Diesel engine test beds. The reading errors of this laminar flowmeter applied directly to measuring the pulsating air mean flow are less than 1-2% comparing with the readings of using plenum camber (damping pressure pulsaitng box). Therefore laminar flowmeter is simple and effctive for pulsating mean flow measurements.