Abstract: The effects of four antioxidants used in catecholamine injections have been examined. Sodium metabisulfite was shown to be the best.Referred to the concentrations of sodium metabisulfite (0.02～0.05%)and EDTA-2Na (0.025～0.05%), and pH value (3.0～3.8), a series of catecholamine injections incorporating these three factors on different levels were prepared based on a Latin square design. Their stability to heat, adverse circumstances and long term storage under room temperature were tested. We found that the lower the concentration of sodium metabisulfite and pH value, within the above mentioned ranges, the morestable the injections would be But the concentration of EDTA-2Na had nothing. to do with the stability.A₁B₁C₁ was chosen as the more optimal prescription, where A₁ represents the 0.02% sodium metabisulfite, B₁ the pH value 3.00 and C₁ EDTA-2 Na of 0.025%. Samples were stored under room temperature for more than a year, and their reaction rate constants were determined. Thus, the reckoned shelf-life may be prolonged for more than seven years. The results, examined by variance analyses, were highly signrficant.