Textile lattice sandwich composite (TLSC) with excellent debonding resistance has been widely investigated. In this paper, the preparation technology of TLSC was improved by foam filling technology, namely hand lay-up and vacuum infusion process, and the flexural properties were studied. The microscope images of TLSC specimens were observed. The structure and resin distribution of TLSC specimens prepared by the above technology was compared. Three-point bending experiments studied the bending properties of foam-filled specimens. The results show that the TLSC specimen prepared by the vacuum infusion process has more resin distribution and high-quality structural form. The obvious resin-rich region appears on the TLSC specimen prepared by hand lay-up. The foam-filling technology can significantly enhance the strength and stiffness of the structure.