Lentil (Lens culinaris L.) is one of the important pulse crops in Iran. The yield of lentil in our country is very low as compared to other lentil producing countries. One of the most important effective factors is water limitation under rain fed conditions in arid and semi arid. In this regard, supplementary irrigation and selenium and molybdenum application can decrease the effects of water deficit and increase nodulation and quantitative and qualitative yield. So, a factorial experiment was performed in a farm near Ardabil city in 2024 using randomized complete block design with three replications. Experimental treatments were irrigation in two levels (rainfed as control and supplementary irrigation at the flowering stage) and  selenium and molybdenum foliar application at four levels (foliar application with water as control, foliar application of 0.5 mg.L^-1 selenium, 15 mg.L^-1 molybdenum, both foliar application selenium and molybdenum). The result indicated that water limitation under rain fed conditions compared to supplementary irrigation at flowering stage decreased yield and some traits such as relative water content, cholorophyll index, effective grain filling period, the number of pod per plant and protein content of seed. Mean comparisions showed that the use of supplementary irrigation and selenium and molybdenum foliar application increased grain filling rate (17.6%), and grain yield (48%) in compared to the no foliar application of selenium and molybdenum under rainfed codition. Also, selenium and molybdenum foliar application increased the number of active noude (1.8 fold) and noude dry weight (24.5%) in compared to the control level. Therefore, with considering of the results of this study, it can be stated that, applying supplementary irrigation at flowering and selenium and molybdenum foliar application can increase grain filling components and quantitative and qualitative yield of rainfed lentil.