Definition：All works over 2 meters(including 2 meters) are considered as working at height. If there is no protection, poor protection or improper operation, falling of people or objects may occur in the high-altitude work at construction site. Human's unintended fall from high is called falling accident, an accident in which an object falls from a height and hits a person below is called an object strike accident. For a long time, it has always been the primary task of construction safety to prevent falling and hitting accidents at construction site.