Biomembranes play important roles not only as a cross-wall to compartmentalize the cytoplasmic components, but also as an interface for various biological functions such as material transport, signal transduction, and energy production. The interplay of phospholipid bilayers and membrane proteins in the biomembranes contributes to realizing sophisticated cellular functions. To investigate the physicochemical nature of lipid bilayers and the mechanism of membrane-related function, various model membrane systems have been developed so far. Lipid nanodiscs, which are aqueous assemblies encompassing the smallest lipid bilayers inside, have attracted much attention in recent years. Compared to conventional vesicles, lipid nanodiscs have several advantages such as uniform small size, dispersion stability in aqueous solution, and easy preparation. Taking advantage of these features, lipid nanodiscs have been applied to the analysis of membrane-associating molecules including membrane proteins. Previously, several preparation methods of lipid nanodisc have been developed, including bicelles formed by the mixture of phospholipids with different hydrophobic chain lengths, complexation of lipid membranes with membrane scaffold proteins, and fragmentation of membranes by amphiphilic polymers. In this paper, we review these strategies for nanodisc formation and discuss the physicochemical properties of nanodiscs based on the analysis of differential scanning calorimetry (DSC).