Babies always cry at night, the following reasons are common: 1, the ambient temperature of the living room is too high or too low, the baby is wearing too thick or too little, insufficient breastfeeding, starvation leading to crying at night.2, vitamin D deficiency rickets, the baby, in addition to crying, the presence of excessive sweating, night terrors, occipital baldness, etc., after giving oral vitamin D gel pills and calcium supplements, it will be gradually improved.3, difficult to raise the type of temperament, everyone has a different temperament, which can be divided into easy to raise type, difficult to raise type and intermediate type. It can be categorized as easy to raise, difficult to raise and intermediate. Difficult to raise type temperament of the baby in the process of bringing up more difficult, to the local child health department to do temperament assessment, to give appropriate training for the baby. 4, the existence of physical illness, such as upper respiratory tract infection, intestinal flatulence.