HDL cholesterol of 0.9mmol/L is abnormal and low; low density, i.e. LDL cholesterol of 2.39mmol/L, is normal. High-density lipoprotein cholesterol is a group of lipoproteins with the highest particle density in serum, and its increased level is beneficial to peripheral tissues to remove cholesterol, thus preventing the occurrence of atherosclerosis. LDL cholesterol, on the other hand, can contribute to the formation of atherosclerotic plaques in the arterial wall and is one of the risk factors for atherosclerosis. Generally speaking, the reference value of HDL cholesterol is 1.03~2.07mmol/L, and its appropriate level should be more than 1.04mmol/L, and when it is less than 1.0mmol/L, it indicates a decrease. The ideal level of LDL cholesterol is <2.6 mmol/L, the appropriate level is <3.4 mmol/L, and its borderline level is between 3.4 and 4.1 mmol/L, and when it is ≥4.1 mmol/L, it is suggestive of elevation. Therefore, when HDL cholesterol is 0.9mmol/L and LDL cholesterol is 2.39mmol/L, it suggests that HDL is on the low side and LDL is at normal level. In this case, dietary control of fat and cholesterol intake and physical exercise are needed. At the same time, screening for the presence of atherosclerosis, acute infection, diabetes, nephrotic syndrome and the use of androgenic drugs, etc., induced by the HDL decreased, and if so, need to address the cause of the disease treatment. It is recommended to consult the doctor in time for the detection of dyslipidemia and to have regular checkups.