The homogeneous co-precipitation method was proposed to synthesize nanoscale binary mixed oxide ZnO–SnO2 in the presence of ethyl acetate. The products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their photocatalytic activity was investigated for the liquid-phase photocatalytic degradation of methyl orange (MO) diluted in water under UV light irradiation. It was found that the coupled oxides ZnO–SnO2 mainly consist of nanosized ZnO and SnO2, and they have better photocatalytic activity for the degradation of MO than ZnO or SnO2 alone. Moreover, the calcination temperature had an obvious effect on the size of the coupled oxide particles.