MgxZn1-xO has been subjects of intense attention as a novel photo-electronic functional material in recent years. In the present paper, MgxZn1-xO powders were prepared by sol-gel method. Effects of Mg contents on MgxZn1-xO structure and luminescence properties were studied. The authors observed that MgxZn1-xO exhibited two kinds of structures, hexagonal wurtzite and face center cubic while x was in the range of 0 and 1. The MgxZn1-xO powders were hexagonal wurtzite structure with x<0.2, face center cubic structure with x>0.2 and their blend structure with x between 0.2 and 0.8. Luminescence spectrum analysis indicated that all MgxZn1-xO samples with various composition showed luminescence of ultra-violet and visible light. The ultraviolet emission peak was from 370 nm to 384 nm and the visible emission peak was around at 468 nm. The average size of MgxZn1-xO powders was about 100 nm.