Abstract: Nanocones with asymmetric shapes and linearly reduced sizes possess a huge application prospect in the field of wide spectrum response. Single nanocones have great potential for the enhanced absorption/scattering and for the surface-enhanced spectroscopy caused by the excitation of surface plasmon. In this work, free-standing single gold nanocones with gradient diameter were fabricated by swift heavy ion irradiation on polymeric templates, followed by latent track etching and electrodeposition processes. The morphology and structure characterizations were performed, included scanning electron microscopy, transmission electron microscopy and optical dark-field imaging. Further dark-field scattering spectrometry results showed that the single gold nanocones have broadband response and multiple polarization modes. In addition, FDTD (the finite-difference time-domain) simulations revealed the mechanisms beneath the broadband plasmonic responses, which are attributed to the variation of surface plasmon resonance modes as a function of the gradually changed diameters of gold nanocone. This work provides an innovative method for the fabrication of high-quality gold nanocones, and also provides systematic theoretical and experimental evidence for the in-depth study of the broadband response properties of single metallic nanocones.