This paper describes detailed wing morphology of some kinds of insects. The structural properties of dragonfly, fly, and mosquito wings were studied. Microscopic observations on the insect wings were examined with a scanning electron microscope. The surface roughness of the insect wings was measured by a three-dimensional, optical shape measuring system. The roughness distribution on the wing surface was presented for some kinds of insects. Some functional principles underlying insect wing design were revealed by the measurements of surface roughness and microscopic observations.