To　improve　the　mode　decomposition　capacity　of　the　empirical　Fourier　transform　for　time-varying　structures,　an　empirical　multi-synchroextracting　decomposition　method　has　been　proposed　and　applied　to　mode　analysis　of　time-varying　structures.　The　multi-synchroextracting　transform　is　introduced　to　obtain　the　time–frequency　coefficients　and　the　time–frequency　spectra　of　response　signals.　Then,　the　time–frequency　energy　of　an　arbitrary　frequency　line　is　obtained　by　summing　the　time–frequency　coefficients　along　the　entire　time　history.　Due　to　the　total　time–frequency　energy　within　the　characteristic　frequency　band　is　larger　than　the　energy　within　an　adjacent　region　outside　the　frequency　band,　an　energy　segmentation　operator　is　constructed　to　determine　the　energy　spectrum　boundaries　for　each　mono-component　signal.　Once　the　boundaries　are　found,　a　zero-phase　filter　bank　and　the　Fourier　transform　are　used　to　accomplish　frequency　spectrum　segmentation　of　the　mono-component　signal.　Finally,　each　mono-component　signal　is　reconstructed　by　employing　the　inverse　Fourier　transform　to　each　segment,　which　realizes　the　mode　decomposition　of　a　time-varying　structure.　The　feasibility　of　the　proposed　method　has　been　verified　against　a　numerical　2DOF　mass-spring-damper　system,　a　numerical　three-story　frame　structure　and　an　experimental　twelve-story　reinforced　concrete　frame　structure.　The　analysis　results　show　that　the　proposed　method　provides　better　precision　than　the　empirical　Fourier　transform　in　the　aspect　of　time-varying　mode　decomposition.　Moreover,　the　proposed　method　has　higher　decomposition　accuracy　in　the　presence　of　high　interference　between　adjacent　frequency　bands.　©　2024　Elsevier　Ltd