The emergence of vertical GaN devices solves the problem of insufficient voltage withstand capacity of horizontal GaN devices. However, the current output capability of vertical GaN devices is not comparable to that of lateral GaN devices. So we propose a Al0.3Ga0.7N/GaN current-aperture vertical electron transistor with a SiO2–In0.05Ga0.95N hybrid current-blocking layer (CBL). Through simulation and in-depth study of the proposed device, the results show that the GaN/InGaN secondary channel enhances the saturation output current of the device, achieving a saturated output current (I DSS) of 985 mA mm−1 and a transconductance (G m) of 256 mS mm−1, which are 30% and 25% higher than that of the single-channel SiO2 CBL device, respectively. The breakdown voltage is 230 V and the on-resistance (R on) is only 0.58 mΩ cm2.