Abstarct: In order to investigate the effect of supplementary irrigation and nitrogen fertilizer on wheat yield, a split plot experiment in a randomized complete block design was conducted with 8 treatments in pahnab and Qarakheil ( research stations of mazandaran agricultural and natural resources research center) in 2017 with 4 replications. in this study, the effect of supplementary irrigation at critical stages of wheat growth and the effect of nitrogen fertilizer on wheat were investigated. The main factor was supplementary irrigation in which the control treatment was rainfed and other treatments were included one irrigation in the flowering stage, one irrigation in the filling stage, two irrigations in the flowering and filling stages. sub - factors include nitrogen application baxsed on soil test and as 25% before planting,25% tillering,25% stem elongation and 25% booting ( equivalent to 200 kg/ha) and nitrogen application at 1.25 times equivalent to soil test 250 kg/ha and ( 25% before planting, 25% tillering, 25% stem elongation, 25% flowering, 25% booting). Results of this study was analyzed separately in two locations. The results of the study in pahnab showed that supplementary irrigation was significant on 1000 - grain weight, spike length, number of spikes and number of infertile spikelet and 1000- grain weight was affected by fertilization. in pahnab, 2 irrigations had better results than other treatments. Although, the effect of fertilization was not significant for many of traits in pahnab,for fertilizing 250 kg/ha, 1000 - grain weight was higher. Qarakheil results showed that irrigation was significantly effective on 1000- grain weight, protein percentage spike length, number of spikes and number of infertile spikelet and grain yield. The percentage of protein and the number of spikes in the interaction treatment were significant, so that in 250 kg/ha fertilizing and 2 irrigations, the protein percentage and the number of spikes were the highest. finally, 2 irrigations in flowering and filling was the best treatment and 250 kg/ha fertilizing had also better results in most traits.