A-linolenic acid is an omega-3 series polyunsaturated fatty acid that is essential for the human body but cannot be synthesized by itself. It is mainly derived from vegetable oils and fats. Due to the generally low ALA content in the oils and fats of bulk oil crops, exploring new germplasm resources and understanding the formation and regulation mechanism of a-linolenic acid are of great significance for the nutrition and diet of oils and the improvement of plant oils. The a-linolenic acid has been detected with abundance in seeds of land plants such as Perilla frutescens, Linum usitatissimum, Eucommia ulmoides, Paeonia suffruticosa, Salvia Hispanica, Agastache rugosa, Elsholtzia ciliate, Actinidia chinensis, Plukenetia volubilis. Fatty acid desaturase such as Δ9FAD, Δ6FAD, Δ12FAD, Δ15FAD is able to regulate the desaturation of the polyunsaturated fatty fatty acid carbon chain. In plants, omega-3FAD is a key enzyme complex that catalyzes the conversion of LA to ALA. The omega-3FAD consists of FAD3 in the plastid and FAD7 and FAD8 in the endoplasmic reticulum. To date, the identification of the omega-3FAD gene family have been greatly accelerated taking advantage of genome and transcriptome studies. Among them, the FAD3 gene is a key gene involved in seed ALA synthesis, whose expression is regulated by multiple transcription factors. For instances, transcription factors such as bZIP, WRI1, LEC, ABI3, FUS3, ASIL1 and PKL are able to regulate the FAD3 gene expression through interaction, and therefore result in the oil content of crop seeds. This paper reviewed the distribution of high-content a-linolenic acid oil plant resources, as well as the fat and fat composition and ALA content of the main oil plant seeds, the basic pathways and key genes of seed ALA biosynthesis, and the types and functions of plant omega-3 fatty acid desaturase, as well as the key regulators of omega-3FAD, in order to provide a theoretical basis for the use of high ALA plant resources and oil plant fatty acid composition improvement.