Abstarct: This study aims to investigate the intercropping of barley and vetch at various levels of nitrogen fertilizer and to determine the optimal planting arrangement. Both quantitative and qualitative characteristics of barley were examined in conjunction with vetch intercropping. An experiment was conducted during the 2017-2018 period at two research stations, Sisab and Shirvan, located in North Khorasan province. The experimental design employed was a split plot baxsed on a randomized complete block design. The main factor consisted of nitrogen fertilizer applied at three levels (0, 50, and 100 kilograms per hectare), while the sub-factor involved various cultivation patterns at five levels: barley monoculture, vetch monoculture, and incremental ratios of vetch density to barley at 15, 30, and 45 percent. The cultivation methods included both mixed and incremental approaches. The characteristics of vetiver investigated included plant height, ash content, biological yield, seed yield, and harvest index. The traits examined for barley encompassed plant height, ash level, neutral detergent fiber (NDF), chlorophyll content above the canopy, days to spike, days to maturity, number of fertile tillers, peduncle length, number of seeds per barley spike, number of spikes per square meter, weight of one thousand barley grains, protein content, and overall barley yield. The mixed crop traits assessed included relative leaf water content, light interception, percentage of green cover, light use efficiency, dry weight of weeds, extinction coefficient, nitrogen content, potassium content, leaf area index, protein content, and fodder yield. baxsed on the analysis of the average interaction effect of nitrogen and mixed cropping components, the highest barley ash content was observed in the mixed cropping treatment of 100:45 with 100 kg of nitrogen fertilizer. Conversely, the lowest ash content was recorded in the mixed cropping treatments of 100:15 and in the pure barley treatment without nitrogen application. The highest barley protein content and weight of one thousand grains were also found in the 100:45 treatment and pure barley cultivation, both with 100 kg of nitrogen per hectare. The results of the three-way interaction analysis indicated that the highest grain yield (1675 kg/ha) was achieved in pure barley cultivation with 100 kg of nitrogen, specifically in the Sisab region. In contrast, the lowest grain yield (790 kg/ha) was recorded in the mixed cultivation of 100:30 with 50 kg/ha of nitrogen, which was associated with the Shirvan region. The land equivalence ratio (LER) in the mixed cropping treatment of 100:45 with 50 kg/ha of nitrogen was the highest (LER = 1.158), also observed in the Shirvan region. The test results demonstrated that the highest seed yield was obtained at a fertilizer level of 50 kg of pure nitrogen per hectare. In addition, each barley plant exhibited the highest performance in pure cultivation. However, when calculating the Land Equivalent Ratio (LER), which directly indicates the increase or decrease in yield from mixed cultivation, the benefits of combining barley and vetch were found to be acceptable.