Reference electrode is an important tool in many electrochemical field. But insufficiency in the performance of commercial Ag/AgCl reference electrodes have been demonstrated in applying to long-time operating devices. To improve the performance of Ag/AgCl electrode, we used electrochemical method using controlling voltage in forming AgCl on Ag. And then heat treatment, polymer coating, and structure change improved the characteristic and long term stability of reference electrode. This fabricated reference electrode realized credible measurement in variety electrolytes.