The crystalline morphology of some FEP copolymers, prepared by different methods, with different hexafluoropropylene (F6) contents was studied by means of small angle light scattering technique.The results obtained show that the main factors which affect the crystalline morphology are the content of F6 and the conditions for crystallization. The morphological structure of these copolymers could change from rod-like to spherulitical, as the F6 content changed from 2% to 14—19% under usual air-quenching condition.However,rod-like crystalline structure would form under very low rate of cooling(0.2℃/min).Some Hv patterns show that fine structure also exists in addition to the two-and three-dimensional spherulites coexisting in the specimens prepared under certain crystallization conditions.