The paper used UV/H2O2 method to remove antiepileptic drug phenobarbital in aqueous solution. The degradation rate of phenobarbital increases with the enhance of H2O2 dosage . The photodegradation speed of phenobarbital decreased with the increase of phenobarbital initial concentration.The optimal pH value for Phenobarbital photodegradation in UV/H2O2 system is 10.9. The existence of Cl- can decrease degradation rate of Phenobarbital. The existence of low concentration of HCO-3 can increase phenobarbital degradation rate,while the high concentration of HCO-3 can decrease phenobarbital degradation rate .The paper applied the ion chromatography and LC-MS-MS to analyze the main product after degradation rate of Phenobarbital,and propose the possible degradation way of ultraviolet of PBB.were detected and identified during phenobarbital photooxidation process. UV/H2O2 has been proven to be an effective method for removal of phenobarbital from aqueous solution.