Duchenne muscular dystrophy, also known as pseudohypertrophic muscular dystrophy and Duchenne muscular dystrophy, is an X-linked recessive disorder. The annual incidence is approximately 1 in 3,500 live births of male infants. Becker muscular dystrophy is also caused by the defective DMD gene, and the clinical symptoms are more severe than those of Duchenne muscular dystrophy. Becker muscular dystrophy is also caused by DMD gene defect, the clinical symptoms appear later than Duchenne muscular dystrophy, the progression is relatively slow, after 18 years of age are still able to walk independently, most can survive to adult 40-50 years or even longer life. According to the clinical manifestations and genetic defects, congenital myotonic dystrophy, Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD) and limb-girdle muscular dystrophy are classified into different types. Among them, Duchenne muscular dystrophy and Becker muscular dystrophy are the most common clinical types, both of which are caused by DMD gene defects, and the following focuses on muscular dystrophy caused by DMD gene defects. Duchenne muscular dystrophy children mostly appear symptoms gradually at the age of 3~5 years old, and most of them are asymptomatic in infancy and early childhood. Some parents who are careful may find that the children are actually slightly behind in motor development since childhood, for example, normal children walk independently at the age of 1 year after birth, but the children may start to walk independently at the age of 1.5~2 years old, or walk unsteadily all the time, which is often mistaken as calcium deficiency or weakness and ignored. As the child grows older, the symptoms become more apparent, and it is often found that the child has poorer motor skills than children of the same age, with uncoordinated and clumsy movements, and cannot keep up with children of the same age in running. The child gradually develops abnormal gait, walking wobbly, commonly known as duck walk, difficulty going upstairs, and difficulty getting up from a squatting position. When getting up from a flat position, the child often turns over to a prone position, raises his head first, holds his knees and thighs with both hands, slowly straightens his trunk and stands up, which is also known as the positive Gower sign. In addition to reduced muscle strength and tone, hypertrophy of the gastrocnemius muscle is often seen on physical examination. The hypertrophy of the gastrocnemius muscle is hard to the touch and lacks the elasticity of the muscle because it is filled with a large amount of hyperplastic fatty connective tissue, so it is called pseudohypertrophy. As the disease progresses, the symptoms of muscle weakness become more and more severe, and the child loses the ability to walk independently around the age of 12. Later, due to prolonged bed rest, bed sores and pneumonic pneumonia may occur. Due to respiratory muscle weakness and heart involvement, the child may die of respiratory failure and heart failure at the age of 20. Becker-type myotonic dystrophy has milder clinical symptoms than Duchenne’s myotonic dystrophy, and the symptoms of muscle weakness appear late and progress slowly, and most children remain able to walk independently after the age of 18. Parents should pay enough attention to their children if they find that they are lagging behind their peers to avoid delaying their child’s condition.