Salt stress has become a significant issue affecting crop growth, and China has abundant saline soil resources. Sugar beet, as a salt-tolerant crop, efficiently utilizes limited land resources. However, severe salt stress can harm the normal growth of sugar beet. To investigate how to improve its salt tolerance, we conducted a hydroponic experiment using Shuangfeng 8 with five treatments: GABA addition (G + S), 3-MPA addition (T) under salt stress (S) conditions, nutrient solution only (CK), and GABA addition (G) as controls. The results indicate that exogenous GABA pretreatment can mitigate reactive oxygen species damage to membrane lipids and stabilize membrane structure by enhancing antioxidant enzyme activity. It also increased the activity of key enzymes in GABA metabolism and GABA content, providing essential substrates for the tricarboxylic acid cycle. This enhanced the activity of key enzymes in the tricarboxylic acid cycle, ensuring cellular energy supply. GABA can link the tricarboxylic acid cycle with nitrogen metabolism, increasing the activity of nitrogen metabolism enzymes and promoting the synthesis of essential amino acids like glutamate. Ultimately, this improves gas exchange and fluorescence parameters, stabilizing photosynthesis, maintaining normal growth of sugar beet under salt stress, and increasing dry matter accumulation. Reverse validation using GABA inhibitors resulted in significantly higher MAD and ROS levels in sugar beet. Antioxidant enzyme activity, GABA content, photosynthetic fluorescence parameters, and dry matter accumulation were lower than in the treatment with exogenous GABA, further suggesting that exogenous GABA at 1.5 mM L-1 can effectively alleviate salt stress damage in sugar beet.