Abstarct: Nowadays, a wide range of studies on organic molecules as an electronic devices and molecular spintronic are being investigated. Organic molecules are used as a molecular channel because of its special properties such as controllable structure, cheapness, flexibility and also a large spin coherence length compare to other common mextal and semiconductors. Poly-Thiophene and its derivatives due to good optical, electrochemical and magnetic properties, has an important priority and therefore uses widely among the electrically conductive polymers. In this research, at first, the structural and electronic properties of pure oligothiophenes (n=1 to 10) and contacted to the sulfur, has been investigated with the approach of density functional theory (DFT) and generalized gradient approximation (GGA) by SIESTA computational code. The results indicates that the magnitude of the energy gap (HOMO – LUMO) exponentially decreases by increasing the oligothiophene length; and pure oligothiophene has no magnetic property, while oligothiophenes contacted to the sulfure from penta thiophene show magnetic property Then, the electronic transport properties of the Au electrode /n-oligothiophenes/ Au electrode molecular wires, for (100) and (111) Au surfaces contacted in two different angles; 0 and 90 degrees, have been investigated by using non-equilibrium Green's function (NEGF), Landaur - Buttiker formulation and TRANSIESTA computation code. The results revealed that current increases by increasing the applied voltage in each oligothiophene and decreases by increasing thiophene rings in a specific voltage. Also for some oligothiophenes, the phenomenon of negative differential resistance (NDR) have been observed. In the next step, the spin-dependent transport properties of oligothiophenes in a tunnel junction, Fe electrode/ n-oligothiophenes/ Fe electrode, for (100) and (111) Fe surfaces have been investigated. The results derived from calculations of the tunnel magnetic resistance (TMR) show that the highest percentage of tunnel magnetic resistance is equivalent to 1730 percent. The results of spin filtering effect (SFE) revealed that the highest percentage is approximately to %96.66 percent. According to the results of this research, the oligothiophenes suggested as a proper candidate for application in molecular spintronics devices, magnetic memory cells and in switching devices.