Currently, low density lipoprotein(LDL) is the main intervention target for coronary heart disease(CHD) prevention and treatment. However, many patients with LDL in the normal range will still develop coronary atherosclerosis. Therefore, domestic and foreign researchers further studied the LDL subgroup and found that small dense low density lipoprotein(sd-LDL) has a stronger atherogenic effect than LDL. sd-LDL, as an independent risk factor of CHD, is more sensitive than LDL. In the past, due to the limitations of detection methods, the detection of sd-LDL has not been widely applied to clinical practice. In recent years, the presence of homogeneous enzyme makes it possible to be used as a clinical routine test. sd-LDL, as a risk factor of CHD, is closely related to its occurrence and development. In the future, more large intervention studies will be conducted to determine the appropriate target level of sd-LDL, and more accurate and effective cardiovascular risk assessment and management treatment will be conducted. This paper reviews the advances in sd-LDL and its relationship with CHD.