Abstract: Because drilling problems can occur when hydraulic oscillators are used to increase the rate of penetration (ROP) in directional and horizontal sectiondrilling, the application and research status of hydraulic oscillators were studied. Firstly, analysis was performed on various hydraulic oscillators in other parts of the world to determine advantages and disadvantages based on their structures. Then, a comparison study was carried out on the velocity improvement between hydraulic oscillators and rotary steering tools based on their field application. And finally, a series of recommendations were proposed. Hydraulic oscillators can decrease friction, improve ROP, shorten drilling cycle and reduce drilling cost. Compared with rotary steering tools, hydraulic oscillators can increase ROP by 29.8% and reduce drilling cost by RMB 380 000 Yuan. In practical operation, however, the application of the hydraulic oscillators isstrongly influenced by improper pumping rate and tools setting, and due to its high pressure consumption, precision instruments (e.g. MWD) may be damaged and resistance to erosion is not satisfactory. In order to solve these problems,it is necessary to continuously improve hydraulic oscillators.