There are various types of membraneless organelles in cells, which play important roles in sensing environmental signals, regulating gene expression, RNA processing, etc.. Biomolecular phase separation has been proven to be the main way of forming membraneless organelles. This article introduces the concept and characteristics of biomolecular phase separation, summarizes research progress of phase separation in plants response to environmental signals, and categorizes the biological functions of phase separation in plants in order to analyze the mechanisms by which phase separation plays a role in plant growth and development and adaptation to adversity, thereby to understand the natures and functions of plant membraneless organelles.