The resonant light absorption and scattering properties of gold nanospheroids were quantitatively studied for their application in photothermal therapy (PPTT) and biological imaging via the T-matrix method with a size-dependent dielectric function. The size parameters, including the minor and major semi-axes, of these Au nanospheroids were accordingly optimized; for the common wavelengths used in PPTT and biological imaging, the optimized nanospheroids exhibited the maximum absorption and scattering at 1064 nm and 1310 nm, respectively, within the range of specified size parameters. The comparison of these results with those obtained by optimized gold nanoshells demonstrated the obvious advantage of these gold nanospheroids for PPTT and biological imaging applications.