Galactomannan is a kind of neutral heteropolysaccharide， which has excellent abilities in thickening， stabilizing and gelling. Moreover， it has a variety of physiological functions， like promoting the proliferation of bifidobacterium in intestine， lowering blood pressure and blood sugar， and preventing constipation， colon cancer， cardiovascular disease. The properties differ in the ratio of mannose/ galactose units， molecular weight， and distribution of individual galactose branches along the main chain. With the development in the hydrocolloid industry， the modification of galactomannan has been an important research topic to ensure its use in food， pharmaceutical， biomedical and other fields. In recent years， there were many researches on galactomannan. The physical properties， physiological activity， modification and application of galactomannan were comprehensively introduced in this paper， in order to provide reference for the research of galactomannan in China.