Contrast, signal-to-noise ratio, resolution and sampling are used as an integrated evaluation standard for the imaging quality of the X-ray in-line phase contrast imaging system. The optimization flow of parameters for the proposed optimized method is erected for the object which has the feature of one dimensional step blurred edge distribution widely applied in many fields. The correlative parameters of the imaging systems under the radiation of sub-micrometer sized focus X-ray source, laser-based micrometer sized focus X-ray source and synchrotron radiation X-ray source are optimized by the means of numerical simulation. The outcome shows that the parameter optimization is completed commendably by the optimized flow. It is obvious that the method can be applied to the optimization of each X-ray source based on simple correction if necessary.