The bacteria that live in the rhizosphere and promote the growth of host plants are called plant growth-promoting rhizobacteria (PGPR). PGPR application helps to reduce the use of pesticides and fertilizers and contributes to the sustainable development of agriculture. Over the past 20 years, significant progresses have been made in both theoretical and applied re- searches of PGPR. This review aims to summarize the mechanisms underlying PGPR growth promotion and disease resistance, including improving nutrient supply and uptake, producing phytohormone and signal molecules, synthesizing volatile organic compounds, and secreting antibiotics. The future research direction of PGPR in both basic and application aspects is also dis- cussed, hoping to provide theoretical reference for future PGPR related research.