Abstract—As a vital component of quadruped robots, the actuator provides the robot with the primary source of power and torque needed to locomote and determine the application performance, such as load capacity, high-speed locomotion, and jumping agility. Over a recent couple of decades, outstanding work has been done to investigate the actuators adopted by quadruped robots, and numerous inquiries about it have been issued. These examination results are grouped into four classes (electrical actuators, hydraulic actuators, pneumatic actuators, and internal combustion engine actuators) according to actuation and then classified and analyzed. According to this basis, we study and sum up the actuators and their performance and efficiency to the robot locomotion and their design techniques. Finally, we give some recommendations for the development of the actuators used in quadruped robots. This analysis aims to summarize various studies and provide enlightenment for robotic designers to develop efficient actuators for quadruped robots in the future.