Liquid liquid phase separation (LLPS) of proteins has been discovered to underlie the compartmentalization of cells, through the formation of liquid biological condensates including membraneless organelles (MLOs), signaling puncta and so on. LLPS is associated with numerous biological processes such as RNA metabolism, gene regulation and signal transduction. However, the fundamental mechanism of protein LLPS still remains to be elucidated. It is important to systematically analyze all the available experimental data for a better understanding of LLPS. To this end, through extensive literature curation, we summarized the proteins and corresponding experimental conditions under which their phase separation tendencies have been detected in vitro, and deposited them in this database.