A method for synthesizing a chiral β-hydroxy acid ester compound is disclosed. The method includes the steps of: using an aldehyde compound and a monoalkyl malonate as raw materials, using a metal and a chiral ligand as a catalyst to make the raw materials be directly and fully reacted in an organic solvent and form a reaction solution, and separating and purifying the reaction solution to obtain the highly stereoselective β-hydroxy acid ester compound. The beneficial effects are mainly embodied in: 1. simple operation; 2. rapidly constructing a highly stereoselective β-hydroxy acid ester skeleton structure molecule; 3. high reaction yield and good stereoselectivity. Therefore, the invention has high basic research significance, industrial production value and social economic benefit.