This work reports first-principle calculations for LiMgP half-Heusler compound doped by the transition metal elements Cr, Mn, Co and Ni motivated by present findings, in which the ferromagnetism conduct is predicted. The studied LiMg0.95Y0.05P alloy (Y=Cr, Mn, Co and Ni) showed the ferromagnetic behavior. The calculations revealed that the main contributions to the net magnetization come from Cr, Mn, Co and Ni. The Cr2+ will have four electrons, in which 2 electrons are in e+ and other 2 occupy the t2+. Then, this orbital is set on the Fermi level. For LiMg0.95Co0.05P alloy, the half-metallic conduct is estimated with 100% polarized on the downside of the Fermi level. Also, LiMg0.95Ni0.05P alloy exhibits the half-metallic conduct on the downside of the Fermi level which is occupied by t2- minority state. This study stated that electronegativity and magnetic properties have correlation with regard to Cr-, Mn-, Co- and Ni-doped LiMgP, in which the trends of partial moments, electronegativity and total moments are MNi chi Co >chi Cr >chi Mn and MLiMg0.95Ni0.05PTot