The invention relates to the technical field of compounds, in particular to a beta-hydroxyl butyryl-amino acid compound, a preparing method and application. The compound comprises compounds with the structural formulas shown in the formulas I, II, III, IV, V, VI, VII, VIII, IX and X, pharmaceutically-accepted salts or solvates of the compounds and pharmaceutically-accepted esterification products.Through rat experiments, cell experiments and safety evaluation, it is proved that the compound can be metabolized into BHB, amino acids and pseudopeptide metabolites in a human body, has an in-vivometabolism time half-life period of 4-6 hours, is safe and free of toxin and side effects, has high stability and certain anti-cancer activity (commonly 30-80 for esophageal cancer cell lines IC50), has good functions for reducing weight, resisting ageing, treating Alzheimer's disease and epilepsy and reducing blood fat and blood pressure, and is expected to become a novel food material for supplementing energy and being developed into different healthcare foods or pharmaceutically-accepted OTC medicines.