Abstract: Glutamine, as the most abundant free amino acid in the human body, plays a crucial role in various physiological processes. These functions include providing energy to cells, supporting immune system function, maintaining intestinal health, and playing a key role in nitrogen transport. Under normal physiological conditions, muscle tissue is the primary site for the synthesis and release of glutamine. After glutamine is released into the bloodstream, it will be transported to the intestines, immune organs or other tissues and play related roles. However, in a state of illness, especially in the presence of tumors, there are significant changes in the metabolism and function of glutamine. The glutamine metabolism can serve as signaling molecules and participates in regulating various signaling pathways within tumor cells, including key pathways that affect cell growth, survival, and metabolism, such as the mTOR and AMPK pathways. This paper reviews the metabolic steps involving glutamine in tumor cells and the role of glutamine blockade in the tumor microenvironment.