Glutamine Synthetase (GS) is a core member of the key nitrogen metabolic synthetase family, widely expressed in human liver, brain, muscle and tumor tissues. It coregulates in vivo glutamine synthesis, nitrogen metabolic balance, cell proliferation and neural homeostasis. GS catalyzes the synthesis of glutamine from glutamate and ammonia, maintains nitrogen metabolic balance, provides key raw materials for cell growth and protein synthesis, and participates in neurotransmitter metabolism and tissue repair. Abnormal overexpression of GS remodels cellular metabolic patterns, promotes tumor cell proliferation, migration and immune escape, and exerts oncogenic effects in liver cancer and glioma, while GS deficiency leads to nitrogen metabolism disorder and neurological abnormalities.