Scaled InAlN/GaN heterostructure field-effect transistors (HFETs) on sapphire substrate with high unity current gain cut-off frequency (fT) and maximum oscillation frequency (fmax) were fabricated and characterized. In the device, scaled source-to-drain distance (Lsd) of 600 nm was realized by employing nonalloyed regrown n+-GaN Ohmic contacts. Moreover, a 60-nm T-shaped gate was fabricated by self-aligned-gate technology. A high drain saturation current density (Ids) of 1.89 A/mm @ Vgs= 1 V and a peak extrinsic transconductance (gm) of 462 mS/mm were obtained in the scaled InAlN/GaN HFETs. In addition, from the small-signal RF measurements, the values of fT and fmax for the device with 60-nm gate were extrapolated to be 170 GHz and 210 GHz at the same bias. To our knowledge, they are the highest values of fT and fmax for the domestic InAlN/GaN HFETs.