There are professional assessment criteria to determine whether a child has language delay, the most commonly used is SS language assessment, parents also need to understand the developmental milestones of normal children for early detection of problems and early medical care, as follows: 1, babies in infancy who do not coo and vocalize or cannot talk to themselves or mutter are abnormal; 2, will not consciously call mommy and daddy, cannot make movements according to instructions, such as pointing to your feet, he has no body language; 3, 18 months old baby can not say 10 words, understanding vocabulary is not enough 50, 2 years old baby can not say sentences; 4, 4 years old can not understand what you say, this time there is a possibility of delayed language development. This is the time when parents should take their babies to the child health department for a physical examination, to have a complete language development assessment and hearing screening to determine if there is a delay in language development, and to seek early guidance and correction from a speech therapist if there is such a problem.