The invention relates to a mold for vacuum filling forming process. The mold is applicable to a thick clamped core structured composite. The mold comprises a base and a forming panel, wherein the base is provided with a central groove, a central thread through hole communicated with the central groove and a stair part around the central groove; the forming panel is supported on the stair part; a plurality of small flow guide holes are formed in the forming panel; an inner sealing groove, an outer sealing groove and a plurality of edge thread through holes positioned between the two sealing grooves are formed in the stair part. The invention further relates to a vacuum filling forming method using the mold. As a downward resin filling method can be adopted, dry spots which are likely to appear inside the composite when the large-thickness or clamped core structured composite is formed by using a VARI (Vacuum Aided Resin Infusion) process are effectively eliminated, and meanwhile as the small flow guide holes are formed in the forming panel, the surface quality of the product is improved.