To provide an apparatus for forming and adjusting a fiber lump fleece composed of cotton or chemical fiber, etc., for the processing of a fiber material delivered from an upstream feed box with a downstream processing equipment and composed of an opening roller rotatable at a high speed and at least one feeding apparatus comprising a feed roller rotating at a low speed and a dish plate.

The uniformity of a fiber lump fleece can be improved and the filling height of the fiber lump in a box can be uniformized by placing a wall element 30a in an upper reserve box 2 in a manner sectionally adjustable in the direction of the depth of the box, providing these wall elements with each one of adjusting member, placing these wall elements within the range of fiber lump fleece forming zone and positioning the individual, dish plates 7, 14 near the wall elements.