Abstract: Sodium percarbonate was prepared by wet crystallization method at low temperature with the by-product of hydrazine hydrate-caustic sludge as the raw material.Concerning to the stabilizer of product，selective tests have been made.Based on the tests the composition and dosage the composite stabilizers have been confirmed.The stability of sodium percarbonate product could be increased by adopting sodium silicate+EDTA (mass ratio：2∶1) composite stabilizer，dosage： 0.35%~0.45% (mass fraction)，or sodium silicate+magnesium sulfate+EDTA (mass ratio：1∶1∶1) composite stabilizer，dosage：0.35%~0.45% (mass fraction).The product quality could meet the Standard HG/T 2764—1996 issued by former Ministry of Chemical Industry.