The magnetic nanoparticle of SmCo was synthesized as thermal decomposition of metal salt by using pyrex bottle in the furnace. The magnetic properties of SmCo-nanoparticle were compared according to the ratio of Sm and Co component. The size of nanoparticle was confirmed by transmission electron microscopy ( TEM) and scanning electron microscopy images ( SEM). The crystal structure of nanoparticle was characterized by X- ray diffraction pattern ( XRD). The magnetic properties were characterized with saturation magnetization from hysteresis loop by vibrating sample magnetometer ( VSM).