At present, most space cameras contain not only panchromatic band with high resolution but also more and more multispectral bands. In order to obtain high signal to noise ratio of multispectral bands for this kind of space camera, sensors with big size element was applied for multispectral bands , so the system parameter Fλ/d turned smaller, and then aliasing problems appeared. Started from the model of sampling optical imaging system, the reasons for aliasing were analyzed, and the method to denote the extent of aliasing by spurious response was introduced. WordView-2 was taken as an example to analyze the aliasing problems of space cameras with panchromatic and multispectral bands. The results show that the aliasing of WordView-2’s panchromatic band is 7.35%, the aliasing of WordView-2’s multispectral bands is 14.76%~18.15%, and the latter is 2~2.5 times of the former. At last, the effects of aliasing and the measures to restrain aliasing were illustrated.