Muscle relaxants are wildly used in general anesthesia to block the electrical activity in nerve muscle joints and paralysis the skeletal muscle. However, there is still a lack of guideline and standard for the use of muscle relaxants in children. The paper introduces the usage of muscle relaxants, the classification of muscle relaxants, the interaction between intravenous anesthetics and inhalation anesthetics and muscle relaxants. It also introduces the muscle relaxant antagonist (sugammadex), as well as the endotracheal intubation under general anesthesia without muscle relaxants in those children who have a high risk of difficult airway. This review summarizes the latest progress of the muscle relaxant in children, aims to guide the rational use of muscle relaxant in clinical practice.