Based on the slender-body theory, the governing equations for the mechanical interaction of one settling fiber with two fixed fibers in fiber suspensions were derived and solved numerically. In order to validate the model and method used in the paper, the interactions of two contact fibers were simulated and the results are in good accordance with the experiments. The results of three interacting fibers show that the initial contact point and the initial orientation angle of settling fiber have a significant effect, however, the angle between two fixed fibers has an insignificant effect, and the initial angular velocity of settling fiber has no effect on the interaction process of fibers. The settling fiber aspect ratio is not an independent parameter involving in the interaction between the fibers. The interaction duration increases as the fiber aspect ratio increases, however, the effect caused by reducing the diameter is more significant than that caused by increasing the length. The interaction duration is directly proportional to the solvent viscosity and verse directly to the fiber specific weight remarkably. Finally, a synthetic parameter A which contains the quantities affecting the interaction duration is derived to uniquely describe the total duration of interaction of the fibers. (C) 2005 Springer Science + Business Media, Inc.