The main purpose of early surgery for children with strabismus is to create conditions for the development of binocular monovision, not just to look good, binocular monovision is commonly known as stereopsis or depth perception, how to experience what is stereopsis? We can cover one eye to try going up and down the stairs, then you will find a kind of stumbling, deep and shallow feeling. Patients with strabismus, although there is no which eye is covered, but one eye strabismus, two eyes can not look at the same target, equivalent to strabismus eye “covered”, its visual effect is the same as one eye is covered. The most important condition for the development of stereopsis is the parallelism of the visual axis of both eyes, that is, the absence of strabismus, especially in the early postnatal period or in early childhood, to maintain the parallelism of the visual axis of both eyes. The most common clinical condition is congenital internal strabismus, that is, internal strabismus that develops after birth or within 6 months after birth, and congenital exotropia that develops within 1 year after birth, the former should be operated before 2 years old. For congenital exotropia, as long as the child has the opportunity to have monocular vision in both eyes, that is, when there is no eye strabismus, by no strabismus we mean that there is the opportunity to look at the target with both eyes at the same time, that is, neither eye is strabismic. In particular, some children with exotropia may not be considered for surgery for the time being if the exotropia only occurs occasionally. However, for those children with exotropia who often fail to maintain an upright position at the onset, surgery should be performed as early as possible, usually before the age of 2-3 years. The difficulty of early surgery in children with strabismus is that it is difficult to measure the degree of strabismus, i.e., the strabismus angle, at this age, and accurate strabismus angle measurement is the key to successful surgery. Another difficulty with strabismus surgery in children is that the surgery must be designed with a long-term perspective, from a developmental point of view, and not just the immediate post-operative results.