Abstract: The shelf-lives of two selected-prescriptions of 10% sodium phenobarbital injections were predicted by accelerated stability test with classical isothermal method (at 100, 90, 80 and. 70℃)and by regressive calculation. It was found that the shelf-life of 10% sodium phenobarbital injection (contain acetamide 20% and propylene glycol 50%) was about 5.47 years at 25℃, which is at least four years longer than that of the current prescription; the shelf-life of 10% sodium phenobarbital injection (contain acetamide 20% and propylene glycol 60%) was about 19.86 years at 25℃, approximately 19 years longer than that of current prescription.It is also found that acetamide can remarkablely stabilize sodium phenobarbital injection. The mechanism of its stabilizing effect is also discussed.