In X-ray imaging system, with the change of parameters in material quality, volume, object distance and else of the target objects, manual adjustments of tube voltage and tube current are often needed to get ideal imaging results. Whereas human interventions are often subjective that cannot meet the automation development of X-ray detection system. In view of the above problems, a method for objective quality evaluation in images which is based on weighted local entropy is presented in the paper. Parameters adaptive adjustment in X-ray detection system can be based on this method. The validity of the approach is proved by experiment and comparative analysis with the traditional image quality evaluation function.