Abstract: The recent development of an integrated PET-CT scanner for the simultaneous acquisition of anatomic(CT) and functional(PET) data in one device offers several advantages such as high sensitivity and accuracy of diagnosis. Its capability of accurate staging of lymph nodes, differentiation of lung lesions and evaluation of the tumor cell's activity makes the determination of lung lesion's characteristic, location, quantitation and staging more accurate. This article reviewed on the value and existing problems of PET-CT imaging in non-small cell lung cancer(NSCLC) for the diagnosis, staging, evaluation of therapeutic effects, determination of treatment strategy and the making of radiation treatment planning.