The formation of electron pairs is a prerequisite for the emergence ofsuperconductivity. While, (anti) ferromagnetism emerges with a long spin order. For this reason, it was believed that these two properties (superconductivity and magnetism) were in competition with each other. Iron is a magnetic element with a large magnetic moment and appeared to be destructive to the emergence of superconductivity. This belief has changed since the discovery of theiron-based superconductor with the combination of LaFeAsO 1-x F x and the critical temperature of 26 K in 2008. The discovery ofsuperconductivity in iron-based layer compounds and the successive increase in critical temperature of these compounds has been a major achievement for the condensed matter community in recent years. The critical temperature (T c ) of 56 K, the critical magnetic field (H c ) of 300 T, and the malleability of these compounds made this achievement highly regarded by researchers. These compounds are the second family of high temperature superconductors after cuprate superconductors. In recent years, various types of iron-based superconductors have been discovered and researched to improve their properties and use in industry. The type of 1111 with the combination of REFeAsO (RE = rare earth elements) is the first group of iron-based superconductors to be discovered. Till now, this group has the highest critical temperature (56 K) among iron-based superconductors. There are other types of iron-based superconductors that are named as 111, 11, 42622, 112, 245, etc. The aim of this thesis is due to the high metal properties of iron-based superconductors such as malleability and other interesting properties of these compounds;Development, upgrading and application of iron-based superconductors in the country. In this research, the combination of SmFeAsO 0.7 F 0.3 isprepared by solid state reaction method. First, to optimize the manufacturing conditions of this compound, we change various factors such as the total duration of the manufacturing process, calcination temperature, final synthesis temperature, duration of heating operations nd quartz tube conditions for the first samples, and finally determine the best conditions for synthesizing this compound. To prepare this compound, we use of Sm graims, Fe 2 O 3 , As, Fe and FeF 3 powders. After synthesis, X-ray diffraction test is performed on the samples to phases detection and determine the crystal structure. Using the electrical resistance test, we determine the critical temperature of the samples. We use the SEM test to observe how the grains formation and disperse and determine their size. Keywords :Iron base superconductor, magnetic, 1111 compound, electrical resistance, phase detection