In this article, the formation of porous permeable iron based composite structure chromized via thermodiffusion method. Chromized porous permeable iron based composites were done by two kind of thermodiffusion process:  first composite samples chromized after sintering (AS) and second composite samples were chromized during sintering (DS) process by pumped and filled with chromium gas in cylindrical chamber. Macro and microstructural properties of the samples were analyzed by optical microscopes NBS-1 and MIM-7, respectively. It is observed that totally change of microstructure due to not perfectly done for the AS samples even 3 h chromizing processes. During preparation AS samples gas phased of chromium moved through the channels of porous composite and deposited on walls of channels. After increasing of keep time the thermodiffusion process is started. It means diameter of the channels became smaller or closed after thermodiffusion process of the composite samples. In another hand, the porous samples structures were changed. In an opposite chromizing results were observed for the DS samples and microstructures were investigated.