Thiamine is a water-soluble vitamin essential for the growth and development of organisms and usually functions as the coenzyme participating in the metabolic processes of nutrients in the body. Protein is a necessary nutrient for human growth and the main source of energy. Therefore, this study was carried out to investigate the relationship between nutrient levels and protein content in shrimps as well as optimize the nutrient ratio in diets to promote shrimp growth performance and improve the utilization rate of feed protein, while also paying attention to reducing pollutants such as ammonia nitrogen generated in the breeding process to effectively reduce the environmental burden on the aquatic environment. To investigate the growth performance and protein utilization of white shrimp diets with different combinations of dietary proteins and thiamine, eight isoenergetic experimental diets with two protein levels (37% and 42%) and four thiamine-supplemented levels (0 mg/kg, 20 mg/kg, 40 mg/kg, and 80 mg/kg) were designed and fed to juvenile shrimps with an initial weight of (0.44±0.05) g for eight weeks under freshwater conditions. Two weeks before the end of the experiment, feces were collected for the detection and analysis of apparent digestibility of nutrients. Before the end of the experiment, the shrimps were subjected to 12-hour fasting, followed by weighing and counting after removal from the net cage to calculate the survival rate (SR), weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and protein deposition rate (PDR). Twelve whole shrimps and hepatopancreas were collected from each cage to assess the composition of whole shrimps and digestive enzymes (protease, lipase, and amylase). After the weighing was completed, the remaining shrimps were returned to the corresponding cages for continuous rearing. After a stabilization period of three days, an ammonia nitrogen excretion experiment was carried out to determine the variations in the ammonia excretion rate of shrimps eight hours after satiation. The results showed that dietary protein and thiamine levels affected the FBW, WGR, and crude protein content of whole shrimps. The growth performances of shrimps fed with high-protein diets were significantly better than those of shrimps fed with low-protein diets (P＜0.05). With the increase of thiamine level in the diets of the same protein level, the FBW, WGR, and crude protein content in whole shrimps initially increased and then decreased. Compared with that of 0 mg/kg thiamine group, the shrimps of 40 mg/kg thiamine displayed significantly higher FBW, WGR, and crude protein content in whole shrimps (P＜0.05). The shrimps fed with diets with thiamine displayed significantly higher SGR, PER, PDR, hepatopancreatic amylase, protease activities, and apparent dietary digestibility of protein and lipids (P＜0.05). The PER, PDR, amylase activity, and the apparent digestibility of protein and lipids of the shrimps fed with low-protein diets were significantly higher than those of shrimps fed with high-protein diets (P＜0.05). The ammonia excretion rate of the shrimps first decreased and then increased with the increase of dietary thiamine level. Regression analysis showed that the optimal dietary thiamine supplementation was 45.14 mg/kg with dietary protein content of 42% and 49.53 mg/kg with dietary protein content of 37%. In conclusion, appropriate levels of dietary protein and thiamine enhance shrimp growth performance by improving the digestive enzyme activities and apparent digestibility while reducing nitrogen excretion. Furthermore, the optimal dietary thiamine level required for maximum shrimp growth decreases as the dietary protein level increases.