Abstract: Based on theories of Darcy-law, micro-element and the fiber spreading, this paper extended the pin-assisted melt impregnation theory which traditionally built for single pin, to multi pins-assisted melt impregnation, in particular for the high viscosity thermoplastic resin. The equation in terms of all of influence factors for multi pins-assisted melt impregnation was developed. The theoretical prediction calculated with assigned parameters was in accordance with the experimental data reported. The results show: pins arrangement for the fiber spreading should be in zigzag as the horizontally-arranged pins has less spread effect; as the fiber tension will raise greatly with adding the number of impregnation pins, which increases the fiber break risk, the number of impregnation pins ought to be 3~5.