We propose a widegap II-VI semiconductor alloy, AlxZn1-xO, a material system for the fabrication of ultraviolet optoelectronic devices. AlxZn1-xO (x=0~0.5) thin films were prepared on quartz glass substrates by sol-gel method. The microstructure analysis of films indicated that the wurtzite structure of ZnO disappeared as the Al doping exceeds 20at%. These films also showed high transmittance in the visible region and the absorption edge had obvious blue shift with the increasing of Al concentration. It was found that optimally ultraviolet Photoconductivity when the Al concentration is 30at% were obtained.