Lack of knowledge about the position,the identification and the radiological characteristics of radioactive materials makes it a difficult work of processing these materials.Gamma-ray imaging technique is a perferable solution to satisfiy the ALARA principle for its ability of providing aforementioned knowledge simultaneously in one measurement at a stand-off distance.Rotating Modulator (RM) multiplexing imaging technique initially proposed for astronomical and astrophysical applications is now introduced to meet need of the measurement.A RM system capable of visualizing and locating the hotpoints or high radioactivity areas by temporal modulation is consisted of a rotating collimator and an array of position-insensitive detectors shadowed by the collimator.Benefit from multiple position-insensitive detectors,it is designed to be a large area,wide energy range imaging system,with much lower complexity comparing to coded aperture systems.Thus imaging of radioactive materials of weaker radioactivity or higher photon energies,e.g.photon energies above l.5MeV,can be achieved through RM imaging rather than coded aperture imaging.As the collimator rotates,the count rate profile can be pre-determined and a raw image of the object scene can be obtained from measured data.An iterative reconstruction method of solving the raw image is then applied to generate the final image approximately.Though geometric angular resolution of RM system is low,simulation results demonstrate the power of super-resolution of the iterative reconstruction method which makes RM imaging a competitive technique to coded aperture.According to the simulation results,our RM prototype is in construction and experimental verification is in progress.