Abstract: Biological mucus is an adhesive substance secreted by both animals and plants, which plays an essential role in biological water-based lubricating systems. For different living organisms, the lubricating mechanisms determined by different components of mucus are distinct. Herein, we reviewed the research progress on lubricating properties of biological mucus, including plant mucilage, animal mucus and synovial fluid. Moreover, some problems were summarized and future developments were proposed. The research on the lubricating properties of biological mucus was of great significance in exploring the nature of tribology and lubrication, and showed potential application values in developing environmentally friendly biological water-based lubricants.