A method and a device for dose modulated X-ray scanning, comprising: setting a target image quality standard for a scanning region, determining a reference data level for the scanning region, calculating a theoretical X-ray scanning dose for the scanning region according to the target image quality standard and the reference data level, calculating the X-ray attenuation difference between each data level corresponding to the scanning region and the reference data level according to the theoretical X-ray scanning dose, determining any one of the data levels corresponding to the scanning region, which X-ray attenuation difference with the reference data level is higher than a threshold as a target to be de-noised, and performing a noise reduction for the target to be de-noised.
