The chromium-zirconium-copper electrode（Cr Zr Cu electrode）and the Al

2

O

3

dispersion strengthened copper electrode（Al

2

O

3

electrode）are used to study the resistance spot welding of 800 MPa high-strength galvanized steel. The weldability of automobile sheets with different electrode materials are investigated. The failure mechanisms of different electrode materials are analyzed by scanning electron microscopy（SEM）and energy disperse spectroscopy（EDS）. The results show that the weldability windows when using Al

2

O

3

electrode is twice as large as that when using Cr Zr Cu electrode under the same conditions

and the tensile-shear load of the welded joint is a little higher than that of Cr Zr Cu electrode. The life of Al

2

O

3

electrode is much longer than that of Cr Zr Cu electrode under the same conditions. The internal cause of the electrode failure is the alloying reaction between the element Cu in the electrode and the zinc layer on the surface of automobile sheet. As the Al

2

O

3

electrode has good heat-resistant property

it can reduce the upsetting on the electrode end face under the action of thermal cycle

and the Al

2

O

3

phase dispersed in the Al

2

O

3

electrode can suppress the alloying of atom Cu and Zn to extend the electrode life.