Abstract: It is quite often to meet with the problem of local interference in engineering design of long distance pipeline. In the experiment, the varying law of local resistance factor (\zeta value) has been studied after combination. It has been shown in the paper that \zeta value would be influenced by the length-diameter ratio between two bends, the direction of flowing fluid, the mutual relation of concerned plane and the suction requirement. It raises the point of interference revision factor C which may be used in the evaluation of head loss for local resistance interference.