Nanosized particles SrMnO3 perovskite was prepared by using sol gel method. The sintering temperature was modified to 700, 1000 and 1200 °C within 6 hours. The effect of sintering in nanosized particles and structural were carefully investigated by using X-Ray Diffractometer (XRD) and Scanning Electron Microscopy (SEM). All the synthesized particles show orthorhombic structure with progression from amorphous phase on lower temperature to single phase on higher temperature of sintering. The crystallite size tends to be constant while the particle size is adjusted. The SrMnO3 grain size also modified to larger as the sintering temperature increase indicating that structure and behavior of the particles could be improved by modified sintering temperature.