This study aims to optimize of P fertilizers unit and alleviation soil salinity stress using irrigation with magnetic water. Two field trial using faba bean (Vicia faba L.; Variety Giza 843), were conducted at Agricultural Experimental Research Station of Tag El-ezz, Agricultural Research Centre, El-Mansoura Province, El-Dakhalia Governorate, Egypt during two successive winter seasons of 2015/16 and 2016/17. The experiment treatments were included two irrigation water treatment (normal and magnetized water) and three doses of P fertilizers (50, 75 and 100% from recommended P application). The two factors were layout in split plot design with three replicates, where the water and P fertilizers treatments were located randomly in the main and subplot respectively. The obtained results indicated that irrigation faba bean plants with magnetic-water treatment surpassed significantly irrigation with un-magnetized water under all dosses of P fertilizers in all recorded parameters except N and Na concentration in soil. Regarding irrigation with magnetic water, the increasing reached 21.45, 24.24 and 40.17% in plant height (cm), fresh plant weight (g) and seed yield (g plant^-1) at harvest compared to irrigation with un-magnetized water of both seasons. As well as the improvements in concentration of N, P and K, Ca and Mg in seeds reached 19.01, 79.59, 49.43, 22.18, and 10.06 % respectively compared to irrigation with un-magnetized water. Finally, irrigation with magnetic water and P fertilizer at rate of 100% from recommended application is considered as most suitable treatment for obtaining the highest yield of faba bean under these experimental conditions.