Pattern formation and transverse effect are reported for azobenzene polymer film.We show,through scanning electron microscopy and polarizing optical microscopy investigation of azobenzene polymer film after being irradiated by degenerate four-wave mixing,that many peak-like islands of azobenzene polymer molecules array in some patterns.Experimental evidence that it is possible to control the photoinduced micro-patterns of the nonlinear organic film via adequately polarized write beams and appropriate power of the write beams,thus making easy growth of nanostructures crystals in azobenzene polymer film.