High‐frequency electromagnetic waves and electronic products can bring great convenience to people's life, but lead to a series of electromagnetic interference (EMI) problems, such as great potential dangers to the normal operation of electronic components and human safety. Therefore, the research of EMI shielding materials has attracted extensive attention by the scholars. Among them, polymer‐based EMI shielding materials with light weight, high specific strength, and stable properties have become the current mainstream. The construction of 3D conductive networks has proved to be an effective method for the preparation of polymer‐based EMI shielding materials with excellent shielding effectiveness (SE). In this paper, the shielding mechanism of polymer‐based EMI shielding materials with 3D conductive networks is briefly introduced, with emphasis on the preparation methods and latest research progress of polymer‐based EMI shielding materials with different 3D conductive networks. The key scientific and technical problems to be solved in the field of polymer‐based EMI shielding materials are also put forward. Finally, the development trend and application prospects of polymer‐based EMI shielding materials are prospected.