The reagent kit for enzyme detection of blood ammonia consists of tromethamine in 50-150 mmol, Tween-20 in 0.1-2 ml, sodium azide om 0.5-2 g, lactose in 5-50 g, glutamate dehydrogenase in 500-1500 u, alpha-ketoglutaric acid in 2-20 mmol, sodium acetonate in 1-10 mmol, and reducing nicotin-amide-adenine dinuclectide phosphate in 0.1-0.5 mmol. After regulating pH to optimal value of 8.0, the components are dissolved, packed and freeze dried and may be cold stored for two years. After being re-dissolved, the components are stabilized at room temperature for 1 week and cold stored to stabilize for 1 month. The reagent kit has powerful interference resistance, medium hemolysis and chylemia, blood sugar below 20 mmol / L, bilirubin below 0.1 mmol / L, enzyme activity loss less than 5 %, MADPH loss less than 10 %, linearity reaching 0.2 mmol / L, CV inside batch of 3.8 % and CV between batches of 5.1 %, and recovering rate of 96.1 %.