I have divided the language backwardness into two types: one, the language backwardness caused by backward intellectual development; two, the language backwardness caused by not backward intellectual development. In the first case, the focus of treatment is not on language, but on intelligence. If intelligence improves, language will improve simultaneously, but if intelligence lags behind, language will definitely also lag behind. Another condition is slurred speech, vague speech, will say a lot, but not easy to understand, this also need to carry out pronunciation training, improve the pronunciation.