This paper demonstrates the dynamic characteristics of 150-V-class GaN power HBTs for the first time. At OFF-state collector bias VCEQ = 80 V, the device shows a low dynamic specific on-resistance (RON,sp) of 0.316 mΩ·cm2, which is only 4.7% higher than static RON,sp, thanks to current conductive path far from the surface. A threshold voltage (Vth) of 3.58 V extracted at 1 A/cm2 is achieved with an on/off current ratio of 2×107. The device also show a large base voltage swing of -7 to 7 V with a small Vth hysteresis of 50 mV. The low dynamic resistance degradation, high positive Vth with low Vth hysteresis, and large base voltage swing all demonstrate the great potential of GaN HBT in power switching applications.