Abstract: In view of the problem that output frequency of traditional ultrasonic oscillation circuit is unstable because of using analog or digital self-excited oscillator, the paper proposed a design scheme of ultrasonic oscillation circuit based on direct digital frequency synthesis technology, and introduced basic working principle of direct digital frequency synthesis technology and implementation of hardware and software of the ultrasonic oscillation circuit in details. The practical application showed that the ultrasonic oscillation circuit with direct digital frequency synthesis chip AD9850 is stable and reliable, and is less susceptible to changes of temperature and humidity, which can completely solve the problem of frequency drift of ultrasonic oscillation circuit of mine-used instrument.