Due to the excellent properties of GaN, such as wide band gap, high electron mobility, high saturation speed, and high breakdown electric field, AlGaN/GaN high electron mobility transistor (HEMT) possesses highly promising applications in the fields of high power, radio frequency, and high temperature applications. However, they are still subjected to the influence of current collapse which strangles its development. Based on the double-pulse technique, the effect of GaN buffer layer trap on the current collapse of AlGaN/GaN HEMT is studied. The results show that the electric field peak at the gate edge is one of the main causes of current collapse. The channel electrons are trapped by the buffer trap under the peak electric field. Because the response speed of the trap in the buffer layer is slow, the channel can not be turned on immediately after the gate voltage has jumped to 0 V, which leads the current to collapse. In this paper, the new structure is proposed by introducing a groove structure in the barrier layer. The channel two-dimensional electron gas is modulated by the groove structure, which influences the channel electric field of AlGaN/GaN HEMT device, reduces the electric field peak at the gate edge, and improves the current collapse effect of the device. Comparing with the traditional AlGaN/GaN HEMT, the inhibition effect of the new device structure on current collapse is increased by 22.30%. The length and height of the groove structure are the critical parameters to affect the new HEMT performance. The optimal parameters of length and hight show that when the length of the groove is 1 μm and the height is 0.01 μm, the current collapse of HEMT and its performance are significantly improved.