Abstract: Proline（Pro） accumulation is an essential metabolic adaptation mechanism of plants under biological and abiotic stress. Its primary function is to act as an osmotic regulatory substance，maintain the osmotic balance inside and outside the cell，and enhance plant stress resistance. It also plays a vital role in free radical scavenging，reducing cellular acidity，and acting as a metal-chelating agent. This paper mainly reviewed the synthesis and degradation of proline，the research status of crucial enzyme genes，biological function，physiological toxicity，ion homeostasis，mechanism of action，and its performance of stress resistance in plants，etc.，to comprehensively understand the research status of proline and provide a reference for its research on plant stress resistance.

Key words: proline, adversity stress, stress resistance, mechanism