Flexible, low-density, high-performance electromagnetic interference (EMI) shielding performancematerials are urgently required in aerospace andflexible electronic devices. Due to the high aspect ratioand conductivity, carbon nanotube (CNTs) has been considered as one of the most promising candidatesfor providing excellent EMI shielding performance. Here, aflexible spongy CNTs consisting of self-assembled, interconnected CNT skeletons, with a density of 10.0 mg/cm3, was directly used as EMIshieldingfilm. The freestanding CNT sponge with a thickness of 1.8 mm shows highly EMI shieldingeffectiveness (SE) and specific SE (SSE) of 54.8 dB and 5480 dB cm3/g in X-band, respectively. The per-formance of the CNT sponges can be further improved by increasing the thickness or density of thesamples. After composited with PDMS by directly infiltrating method, the CNT/PDMSfilm still exhibitsexcellent EMI SE (46.3 dB) at the thickness of 2.0 mm, while the CNT loading content is less than 1.0 wt%.The EMI SE of the composite is almost unchanged after repeated stretching or bending for 1000 cycles.Theflexible, stability, and highly conductive nanocompsite can be directly used as high-performance EMIshieldingfilms in areas such as packaging, electronics and communication.