An attenuation correction method and device for an image in a PET system. The method includes: acquiring transmission scanning sinogram data from a PET apparatus reconstructing the transmission scanning sinogram data with Bayesian model-based Ordered Subset Expectation Maximization (OSEM-B) algorithm and Filtered Back Projection (FBP) algorithm, to obtain an OSEM-B attenuation image and a first FBP attenuation image respectively performing a weighted calculation on the OSEM-B attenuation image and the first FBP attenuation image to obtain an effective attenuation image and performing attenuation correction on emission scanning sinogram data from the PET apparatus by using an attenuation sinogram generated based on the effective attenuation image.
