Abstract: Graphene-based electromagnetic wave absorbing materials have received great attention. In this paper, cavity cubic few-layer graphene was synthesized by solid-phase pyrolysis using sodium chloride as the template and phthalocyanine as the carbon source. In the preparation process, the sodium chloride cubic template was prepared by the antisolvent method and the homogeneous mixing of carbon source and template was achieved simultaneously. The experimental results show that the products obtained by pyrolysis at 700 °C can achieve an effective absorption bandwidth of 6.7 GHz with a filler loading of only 4 wt% and a coating matching thickness of 2.5 mm.