A method for reconstructing a PET image using GPU parallel computing including the following steps: 1) sampling particles of each voxel and obtaining an intensity value of each particle of the voxel 2) calculating a prior intensity value of the voxel, and calculating a weight value of each particle of the voxel corresponding to the intensity value of each particle 3) resampling the intensity value and the weight value of the particle, and obtaining the resampled intensity value of the particle and the resampled weight value of the particle 4) repeating step 2) and step 3) until the resampled intensity value of the particle is converged to a certain value and 5) calculating the voxel value according to a true intensity value of the particle and a true weight value of the particle.
