An x-ray imaging technology, performing an x-ray dark-field CT imaging of an examined object using an imaging system which comprises an x-ray source, two absorbing gratings G1 and G2, an x-ray detector, a controller and a data processing unit, comprising the steps of: emitting x-rays to the examined object； enabling one of the two absorbing gratings G1 and G2 to perform phase stepping motion within at least one period range thereof； where in each phase stepping step, the detector receives the x-ray and converts it into an electric signal； wherein through the phase stepping of at least one period, the x-ray intensity at each pixel point on the detector is represented as an intensity curve； calculating a second moment of scattering angle distribution for each pixel, based on a contrast of the intensity curve at each pixel point on the detector and an intensity curve without presence of the examined object； taking images of the object at various angles, then obtaining an image with scattering information of the object in accordance with a CT reconstruction algorithm.
