Abstract: The work done by a fiber bundle in the mold was analyzed for the wavy curved runner impregnation mold， and the fiber bundle broadening model including process and equipment structure parameters was constructed according to the principle of energy conservation. The influence of process and structural parameters on the width of the fiber bundle in the mold was explored by using the wavy curved runner impregnation mold designed in the laboratory. The results indicated that the process parameters generated a great influence on the fiber bundle broadening. Among these parameters， the traction tension was the main influencing factor， and the equipment structure parameters also had an impact on the width expansion to a certain extent. The model can effectively predict the unfolding width of the fiber bundle in the mold impregnation stage， which provides a theoretical basis for controlling and optimizing the fiber bundle broadening process in the mold.

Key words: fiber broadening, melt impregnation, prepreg tape, conservation of energy