The gut microbiota (GM), as a complex ecosystem, exerts influences on human body structure, endocrine levels, metabolic capacity, nervous system, and immune function. It has been discovered that the diversity of GM decreases dramatically with ageing, and even undergoes harmful transformations in functional structure, jeopardizing the health of elderly individuals. Since GM is modifiable, this review systematically analyzes research progress on the role of GM in elderly endocrinology, skeletal muscle systems, cognitive-psychological functions, neurological disorders, and viral infections, while exploring underlying mechanisms. The objective is to investigate novel therapeutic approaches and potential targets for age-related diseases, and to provide references for future GM-omics studies.