Pectin is a natural polysaccharide present in the cell wall of higher plants, which plays an important role in the textual and nutritional properties of fruit and vegetable-based products. There are two types of pectin: high methoxy pectin (HMP, with methoxy content ≥ 7%) and low methoxy pectin (LMP, with methoxy content < 7%). LMP has good stability, gelling and thickening properties, and is widely used in dairy products since it brings a special flavor to fermented milk and increases the viscosity and stability of the product. However, the yield of LMP is low due to the limitations of production and processing conditions. Therefore, the conversion of plant-derived HMP into LMP through de-esterification can meet the industrial demand for LMP. This review outlines the current status of the application of LMP in the dairy industry and its preparation methods including acid de-esterification, alkaline de-esterification, enzymatic de-esterification and amidation, and discusses the effects of these methods on the structure of pectin. Hopefully, this review will provide a theoretical basis for the industrial production and wide application of LMP.