The development of the latest generation of electronic industry has requirements of wearable, portability, comfort, etc. In recent years, the design and fabrication based on flexible actuators have become the state of the art in the field of commercial consumer electronics and scientific research. Compared with rigid actuators, flexible actuators are more portable, flexible, and easier to be conformal to human skin. With these characteristics, flexible actuators show the great potentials in human-machine interfaces, such as creating a variety of haptic feedbacks which mimic the sense of real touch (knead, press, and pull). In addition, the whole devices can be made with portable and cost-effective process. The research and development of flexible actuators used for haptic force feedback are analyzed from the functional materials and their correspondingly working principle in this review. Different working mechanisms are discussed based on their advantages and disadvantages of flexible actuators. In addition, the paper concludes the potential applications of flexible actuators in augmented reality, virtual reality, education, and medical assistance, etc. The existing difficulties of flexible actuators used to achieve haptic force feedback are also summarized. Flexible actuators with safe, comfortable, portable, beautiful, and quiet characteristics are key features to be merged with future human-machine interfaces.