Electromagnetic interference (EMI) shielding materials with high performance and low density are urgently needed with the rapid development of electronic communications. In this work, tuning solid-air interface of graphene paper was carried out to enhance multiple reflections of incident electromagnetic waves for high-performance EMI shielding. The large amount solid-air interface (57.8 m(2) g(-1)) endowed the porous graphene paper with a high EMI shielding effectiveness (SE) of 31.0 dB, 50% enhancement from its counterpart of solid graphene paper. This porous graphene paper also showed an ultralow density of 0.02 g cm(-3), an 18.5-fold decrease from its counterpart of solid graphene paper. Moreover, the EMI SE of obtained graphene papers exhibited proportional relationship with their specific surface area, further confirming the vital role of solid-air interface in the enhancement of EMI shielding. This work quantitatively demonstrates the significance of solid-air interface area for enhancing the EMI shielding performance and proposes an efficient guideline for the design of high-performance and low-density EMI shielding materials.