This paper aims to design and construct a Langmuir probe diagnostic system for plasma parameters measurement in the Iranian Inertial Electrostatic Confinement Fusion (IR-IECF) device. For this purpose, a Langmuir probe diagnostic system is designed and constructed to determine the plasma parameters such as temperature, ion and electron density, and potential. Considering the characteristic of the plasma source of IR-IECF, the electrode selected for the probe is a tungsten wire with a diameter and length of 0. 3 and 1. 5mm, respectively, protected by an alumina ceramic tube with an inner diameter of 0. 7cm. The connections and probe holder base on the vacuum chamber are stainless steel. The electrical circuit of the probe provides voltage and current of 500v and 1mA, respectively. The obtained results demonstrate that between two electrodes and at a distance of 25mm from the external electrode, the electron temperature, the electron density, the plasma potential, and the ion density are 50. 1 eV, 3. 1×1015 1/m3, 198V, and 0. 4×1015 1/m3, respectively.