Abstarct: Application of mycorrhizae is a method to improve yield and water deficiency tolerance in crops. Mychorrhizae is one of the biological part in soils. Their useful characteristics have promote scientific investigations and eagerness toward commercial applications of the fungi as biological manures. Incorporating mychorrizhae in soil promotes growth and yield of the crops both in laboratory and farm. Mychorrizhae increase nutrition uptake through promotion of root development in a given area, hence, change the plant-water relations and improve water deficiency tolerance and water use efficiency. In this investigation, the effects of arbuscular Mychorrizhae and humic acid on the yield and water use efficiency of maize crop under three irrigation systems was studied in a field experiment.The research was conducted using a split plot factorial experiment baxsed on randomized complete block design with three replications. The main plot was water deficit condition (100% FC,66% FC,33% FC) and sub plot included application of two species of mycorrhizae, M0: non application of mycorrhizae, M1: Glomus mosseae and M2: Glomus intraradices. The other factor was humic acid in two levels of application(H1) and non application(H0).Our results showed that water deficit condition decreased plant growth, yield and yield components compared to control, whereas,inoculation with mychorrhizae increased growth, yield , yield components and WUE of the treated crops compared to control. Humic acid led to results approximately similar to those of mychorrhizae. Interaction of mychorrhizae and water deficit condition in final harvest was significant on 100 seed weight and WUE, so that the highest rate of WUE was observed in 33%FC and symbiosis of G. mosseae. Interaction of Humic acid and water stress, Humic acid and mychorrhizae and triple interaction (water deficit condition × Humic acid × mychorrhizae) had no significant effect on studied parameters of maize crop through many developmental stages of the crop