A series of Mg

x

Zn

1-x

O(0≤x≤0.3)thin films were successfully fabricated by sol-gel method.The structural and optical properties were studied using XRD and photoluminescence spectrum.The results indicate that the Mg

x

Zn

1-x

O thin films have hexagonal wurtzite single phase structure and a preferred orientation with the c axis perpendicular to the substrate.It was observed that there is an critical annealing temperature(700℃)of the Mg

x

Zn

1-x

O(0.1≤x≤0.3)thin films preheating at 350℃

when annealing below this temperature

the intensity of(002)XRD peak increased

and the PL spectra of Mg

x

Zn

1-x

O(0.1≤x≤0.3)thin films show both UV emission and green emission;when annealing above this temperature

the intensity of(002)peak decreased while(100)and(101)peak appeared

and the PL spectra of Mg

x

Zn

1-x

O(0.1≤x≤0.3)thin films show only UV emission.The impurity concentration also affect the emission

when annealing below 700℃

the PL spectra of pure ZnO thin films show only UV emission

while the PL spectra of the Mg

x

Zn

1-x

O(0.1≤x≤0.3)thin films show both UV emission and green emission.