Cleft lip and palate is a congenital disease that mainly affects the aesthetics of the child, while the main effect is the child’s pronunciation. The cause of cleft lip and palate is not fully understood. It is generally believed to be more directly related to genetic factors, as cleft lip and palate itself has an obvious family aggregation. However, cleft lip and palate is not a completely hereditary disease, as many parents of cleft lip and palate parents do not have cleft lip and palate in their parents or even in previous generations. Current research suggests that there are conditions that occur in the first 3 months of pregnancy that may also lead to cleft lip and palate. For example, exposure to teratogenic drugs during the first trimester, or viral infections during this time period, or bad habits such as smoking, drug use, or more serious changes in a woman’s psychological state during this time period may cause cleft lip and palate to occur. Therefore, in conclusion, cleft lip and palate is related to the congenital genetics and the environment in the first trimester of pregnancy.