The MLEM(Maximum Likelihood-Expectation Maximization) algorithm is used to reconstruct the distribution of source based on the principle of MURA(Modified Uniformly Redundant Array) coded aperture imaging.Through numerical analyzing

the distribution of single energy 413 keV

a plane-source on the image plane is obtained.The reconstruction result by the MLEM algorithm agrees with the original distribution.Then

through the simulation of coded aperture image for the hypothetical Pu component by MCNP

and the image reconstruction of the source

the method based on coded aperture imaging to measure the symmetry attribution of plutonium component is validated.The numerical simulation result shows that coded aperture imaging is more advantage than pinhole imaging to measure the symmetry of Pu component in the fields of detection efficiency of gamma ray and protection of sensitive information.