Abstract: Lactobacillus plantarum has attracted many research attention because of its probiotic function. The proteolytic system of Lactobacillus plantarum is incomplete. Peptide transport system and intracellular peptidase exist,but the lack of cell wall protease results in the inability of the bacteria to directly utilize the protein in milk and therefore the growth in milk is poor. Co-fermentation of lactic acid bacteria(LAB)with strong proteolytic ability and L.plantarum in milk is a solving solution,the former can degrade protein primarily to peptides and free amino acids,which supply nitrogen source to L. plantarum and promote its growth. Research progress of L. plantarum is summarized,including its probiotic functions,reasons of poor growth in milk and relative solutions(adding nutrients,adding proteinase and co-fermentation).