Searching for superhard metallic carbon materials has always been an enduring topic in scientific research. In this work, based on first-principles calculations combined with RG2 method, three new sp2–sp3 hybridized superhard metallic carbon phases were proposed, namely, Fddd-C96, Ccca-C32, and Ibam-C48. The structural, mechanical, and electronic properties of these phases are systematically studied. The results show that they are dynamically, thermally, and mechanically stable. The hardness of Fddd-C96, Ccca-C32, and Ibam-C48 are 77, 69, and 43 GPa, respectively. Electronic properties show that all three materials are metallic, the origin of metallicity mainly comes from sp2 hybridization. To compare the properties of carbon materials with high superhardness and low energy, a P parameter was defined. We find that only two carbon allotropes in the well-known Samara Carbon Allotrope Database have higher P parameters than Fddd-C96. The method of P parameter can quickly screen out materials that meet expectations from a large amount of data based on the characteristics of the materials. These three structures are expected to become candidate materials for high-pressure electronic devices.