Abstract: In order to improve the seismic performance of tunnels crossing active faults, this paper starts from the energy response of the structure, introduces the factor of fault misalignment, optimises the calculation theory of the energy response of tunnels crossing active faults under the action of earthquakes, puts forward the method of calculating the energy response curve of the tunnels under the action of earthquakes and fault misalignment according to the relationship between the input energy and the intrinsic energy of the structure, establishes the method of distinguishing the zone of seismic damage impacts in the tunnels crossing active faults, and carries out the application research relying on the active fault section of the F5 of the Longdongzi Tunnel. The results show that the destabilisation damage of the F5 active fault segment occurs around 10 s after the earthquake, with a maximum damage rate of 58%; seismic impact zones for tunnels through active faults based on the damage rate, According to analysis the seismic hazard information of the F5 active fault section of Longdongzi Tunnel in Wenchuan Earthquake, the type and distribution of seismic hazards on the site are more consistent with the seismic hazard impact zone of this paper. It shows that the seismic impact zone method for tunnels through active faults based on the energy principle proposed in this paper can be used in engineering practice. The research results can provide an reference for the anti-seismic design of tunnels through active faults.