The PXM (Projection X-ray Microscope) end station was used to complete a preliminary test at the SPring-8 12B2 beamline. The x-ray through scintillator and knife-edge become visible-light image can get from the sensor. The knifeedge image has an edge shape, which can create the edge response line. The edge response line can be differentiated from the point response line. The point response line can then be transferred by Fourier transformation, and achieve MTF (Modulation Transfer Function). Here we apply Chebyshev polynomials to fit the edge response line and calculate the MTF. We used 20× and 50× objective lenses to generate the knife-edge images and calculate the MTF value. We found that the scintillator design resolution is 1 μm, and following the MTF calculation, the image resolutions are about 3 μm and 1.4 μm in the 20× and 50× objective lens, respectively.