When the amount of amniotic fluid is <300ml and the amniotic fluid index is <5cm, it can be diagnosed as oligohydramnios and caesarean section is recommended to terminate the pregnancy. The causes of amniotic fluid hyponatremia are mainly fetal urinary tract malformation, expired pregnancy, placental insufficiency, fetal growth restriction and other factors. The adverse effects of low amniotic fluid can severely affect the development of the fetal lungs, causing the fetus to develop atelectasis, which in turn leads to intrauterine hypoxia or even stillbirth, and may also lead to the development of extrusion syndrome in the fetus. In case of low amniotic fluid, the treatment plan is chosen according to the presence or absence of fetal anomalies and the size of the gestational week, which can be supplemented by drinking more water or coconut juice. The fetus should also be further examined for urinary and digestive malformations. When full-term pregnancy is combined with placental malfunction, fetal distress or low amniotic fluid at rupture of membranes and severe fecal infections, termination of pregnancy should be done by cesarean section to reduce perinatal mortality. Those with less than one month of gestation and fetal lung immaturity can be treated for the etiology, try to extend the gestational weeks, and terminate the pregnancy if necessary according to the gestational age and intrauterine condition of the fetus. If the fetal chromosome examination does not show any abnormality, amniotic fluid infusion can be chosen to replenish.