In 1984, a consensus was reached by the China Pediatric Dermatology Research Collaborative Group on the diagnosis of “pediatric frictional mossy rash”. The etiology of pediatric friction mossy rash is still unclear, but it is mainly related to contact with frictional irritation and viral infection. Spring is the most common season for pediatric friction mossy rash. The disease often occurs in preschool-age babies, such as children playing with sand, water, soap, laundry detergent blowing bubbles, toys, and Play-Doh, but some experts believe that it is related to sun exposure factors. Babies at this age have poor autonomy, are active, and do not pay attention to contact and posture, so as long as the exposed skin is prone to rashes. The initial rash appears as a few small rice-sized skin-colored papules scattered on the back of the hands, without itching, gradually increasing in number and gradually spreading to the wrists, forearms, elbows and knees, with the rash gradually becoming red in color and itching gradually appearing, with some children feeling itchy and spreading to the whole body after 3 weeks. Pediatric friction mossy rash because the etiology is not clear, the current treatment is mainly symptomatic, avoid sand and external adverse stimulation, strengthen the care of children, reduce mechanical friction. And treatment is not sensitive, but some children may heal themselves in about 2 months.