Sapphire is excellent mechanical properties that used as substrate of light-emitting diode epitaxial and screen protective film of cell phone, but it is quite difficult machining. This study used a different voltage, the time and the proportion of the electrolyte,A study on sapphire machining by electrochemical discharge machining. Observation and comparison of experimental results and found that the voltage 80 voltage, 60 seconds and electrolyte mixture of phosphoric acid and sulfuric acid, sulfuric acid, accounting for 55.56%, the mechining depth is 24.4663μm, that is the largest working depth of the study, and this mechining efficiency is also higher than the industry using sapphire machining by wet etching, and no heat affected zone, such as laser processing, sapphire able to prove the feasibility of electrochemical discharge machining methods of processing.