In order to evaluate the effects of density, nitrogen fertilizer and mowing height on yield, dry matter and other agronomic attributes of kochia (Kochia scoparia L.), an experiment was conducted in a factorial based on a randomized complete block design with three replications in the spring and summer at Research Field of Islamic Azad University in Neyshabur, Iran during 2011. The treatments were included: plant density in three levels (20, 30 and 40 plants m^-2), mowing height in two levels (10 and 20 cm) and nitrogen fertilizer in two levels (consumption of 150 N kg ha^-1 as urea after the first mowing and non-consumption of nitrogen fertilizer). Results indicated that the effect of plant density was not significant for ratio of leaf to stem at the both first and second mowing, while its effect on the yield was significant for the first and second mowing. Moreover increasing plant density significantly increased the dry matter yield. The effect of mowing height on measured traits and the effect of nitrogen after the first mowing on the yield of dry matter was not significant, but its effect on ratio of leaf to stem in second mowing was significant. In the first and second mowing, there was not any significant correlation between the yield of dry matter and leaf dry weight, but there was a positive and significant correlation between the yield of dry matter and stem dry weight. Overall, 30 plants m^-2, mowing height at 20 cm and nitrogen fertilizer consumption following first mowing are useful to obtain desirable yield and quality of forage of kochia production.