The risk factors of human cardiovascular diseases are related to plasma cholesterol levels. The major carrier of plasma cholesterol is lipoprotein. Lipoprotein structure-function relationship provides important clues that help identify the role of lipoproteins in cardiovascular disease. The structure determination of lipoprotein is challenging by using traditional approaches, such as X-ray crystallography, nuclear magnetic resonance spectroscopy, mass spectrometry and cryo-electron microscopy. The compositional and conformational heterogeneity of lipoproteins are major barriers to the identification of lipoprotein structures. Recently, Ren et al. reported an optimized negative-staining protocol to directly visualize the structure of each individual lipoprotein particle. The statistical analysis validated this protocol in examining lipoprotein structures. The high-quality image of lipoprotein provides a basis for three-dimensional structure determination of a single lipoprotein. Moreover, this protocol can be used as a general protocol to examine and screen molecular drugs for treating human diseases.