Many parents believe that strabismus does not affect their children’s eating, drinking and playing, so it is the same whether the surgery is done early or late. Some parents are reluctant to give their children strabismus surgery because they are afraid that their children will be too young to undergo surgery and will wait until they grow up. So when is the best time to operate for children who need strabismus surgery? From the viewpoint of visual development, children aged 0~3 are the critical period of binocular vision development, and 3~8 are the sensitive period. If strabismus appears within this age, the unconsolidated binocular vision will be easily destroyed, and then monocular vision will be formed. Also during this period, if the skewed eye position is corrected in time, the plasticity of the retinal correspondence is great and binocular vision can be re-established. As the age grows, once a solid abnormal retinal correspondence is formed, it is difficult to form and reconstruct binocular monocularity even if the skewed eye position is surgically corrected. The surgery serves only to improve the appearance. The purpose of strabismus surgery in children is not only to correct the eye position and improve the appearance, but more importantly, to cure the visual function. Therefore, clinically, for children with common strabismus, as long as the visual acuity of both eyes is basically balanced or close to normal and they can cooperate with strabismus examination, early surgery is recommended, generally at the age of 3 to 6. Children with congenital paralytic strabismus should be operated as early as possible. Because of the early onset of congenital paralytic strabismus and the long-term existence of compensatory head position due to strabismus, it will lead to spinal curvature and facial asymmetry, which will not be recovered by adults. Early surgery can create the conditions for normal binocular vision development in children. In children with acquired paralytic strabismus, the first step should be to treat various primary diseases, and after conservative treatment, observe the change of strabismus for about six months, and consider surgery after the strabismus is stabilized.