This paper demonstrates the dynamic characteristics of 150-V-class GaN power HBTs for the first time. At OFF-state collector bias V_CEQ = 80 V, the device shows a low dynamic specific on-resistance (R_ON,sp) of 0.316 mΩ·cm², which is only 4.7% higher than static R_ON,sp, thanks to current conductive path far from the surface. A threshold voltage (V_th) 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 V_th hysteresis of 50 mV. The low dynamic resistance degradation, high positive V_th with low V_th hysteresis, and large base voltage swing all demonstrate the great potential of GaN HBT in power switching applications.