Pulse-modulated discharge is an effective way to improve the stability of radio-frequency (rf) discharges. Previous studies have shown that with the power frequency increasing to the ultra-high frequency (UHF) band, the introduction of pulse modulation in rf discharges will bring about new discharge behaviors. In this paper, the fluid model is adopted to numerically investigate the new discharge characteristics in dielectric barrier discharges (DBDs) with the rf frequency larger than 500 MHz. A very large current peak occurs in the first positive and negative half cycle during the power-on phase, respectively. The spatial structure of electric field is given to further understand the underpinning physics of the large current peaks. Furthermore, the effects of duty cycle, modulation frequency and voltage modulation rates on the large current peaks are examined based on the computational data. This numerical study will deepen the understanding of DBDs modulated by pulses in the UHF band.