For dual-active-bridge (DAB) DC/DC converter, when conventional pulse width modulation (PWM) is used, large harmonics are generated at the switching frequency and frequency multiplication, resulting in conductive electromagnetic interference (EMI). The random PWM technology can improve the electromagnetic compatibility of the system by dispersing the harmonics of the switching frequency and frequency multiplication. This paper studies the application of Random Carrier Frequency Modulation (RCFM) in DAB converter and analyzes its advantages and disadvantages. Based on this, an improved random PWM technology is proposed. On the one hand, the electromagnetic compatibility of the system is improved by using the random variation of switching frequency; on the other hand, the fluctuation of transmission average power is eliminated through the periodic processing of the random modulation signal. Finally, the simulation shows the feasibility of the technology.