It is urgently and practically significant to optimize the sample pretreatment, and to establish accurate detection of folic acid content in food and the presence of folic acid, in order to promote the in-depth research of various aspects of folic acid. In the paper, the molecular structure of folic acid and its main forms, as well as the content of folic acid in common foods are introduced. The sample pretreatment methods such as chemical method and enzymatic hydrolysis method are described. It is indicated that the enzymatic hydrolysis method is more suitable for the determination of folic acid in foods such as beans and grains, so that the folic acid combined with protein, starch and the like is fully hydrolyzed by using a combination of protease and amylase. The common methods for detecting folic acid, such as microbial method, fluorescence analysis method and high performance liquid chromatography (HPLC), are reviewed. HPLC is characterized by high efficiency and precision, especially ultra-performance liquid chromatography-mass spectrometry/-mass spectrometry (UPLC-MS/MS), which can quickly determine different forms of folic acid. Factors affecting the stability of folic acid and measures to increase folic acid intake and stability are explored.It shows that the measures to increase folic acid intake and stability includes adding folic acid in staple crops, packaging folic acid with protein capsule, facilitating the combination of folic acid and protein, etc.