Abstract: Electron transpiration cooling is a new type of hypersonic active thermal protection technology that utilizes the thermionic emission effect of materials. The thermal load is transferred to the downstream of the flow field by the emitted electrons, reducing the peak value and gradient of the heat flux. The electron transpiration cooling will open door to hypersonic thermal protection system designs previously unattainable. As a potential cooling technology, the working principle and technical characteristics were introduced in detail in this paper. Also, research progresses on electron transpiration cooling were reviewed and key issues needed to be addressed for further development were discussed.