With the application of complex structural well technology such as large inclination well, horizontal well and horizontal branch well in petroleum exploitation industry, the problems of pressure support and sticking are increasing. In order to solve these problems, a hydraulic oscillator is designed. When drilling fluid flows through the hydraulic oscillator, the hydraulic oscillator generates mild oscillating forces and is transmitted through the drill tool to the drill bit, thereby reducing the friction of the drill tool on the wall, reducing the possibility of pressure and sticking. In order to verify the rationality of the design, Simulink is used to simulate the dynamic characteristics of the screw motor in the oscillator. The results show that the speed of the screw motor fluctuates from 0 to 0.01 s, and the stable speed of 6.8 r/s will be reached after 0.01 s. Finally, the prototype is trial-produced and tested. The working pressure of the prototype is 3.8 MPa and the vibration frequency is 14.7 Hz, which meets the design requirements.