The ZrO

2

-Y

2

O

3

-MgO powder is prepared by wet-mixing after designing the composition and phase content.Sintered sample which has different amount of monoclinic and tetragonal phase at room temperature is obtained at different sintering temperature.The grain size is investigated by X-ray pattern.The result shows that the content of monoclinic ZrO

2

is increased and the content of tetragonal ZrO

2

is decreased with the addition of Y

2

O

3

.The sintering temperature has little influence on the phase transformation.Meanwhile the sintering temperature and the Y

2

O

3

content have little influence upon the grain size.