The formation of fatty liver is due to the accumulation of fat in the liver cells, the process is relatively long, the exact time varies from person to person, can not be generalized. Fatty liver, also known as fatty liver disease, is a disease in which fat accumulates in liver cells due to long-term alcohol consumption, obesity or diabetes, metabolic syndrome, and other underlying diseases. It is a disease in which diffuse steatosis of the liver cells is the main pathological feature, and can affect the normal function of the liver. The process of fatty liver formation is relatively long, when the liver cells have 5%~32% steatosis, it is mild fatty liver, when 33%~65% steatosis, it is moderate fatty liver, when 66% or more steatosis, it is severe fatty liver. The accumulation of fat in the liver cells is a long-term process, which varies from months to years depending on the individual’s physical condition and the presence or absence of underlying diseases, and cannot be generalized. When fatty liver is detected on examination, it is recommended to seek prompt medical attention and receive active treatment to avoid delaying the condition.