To evaluate the effect of living mulches on weed control and yield of Black cumin (Nigella sativa L.) weeds by living mulch, a factorial split experiment was conducted in the form of a randomized complete block design with four replications in the research farm of Aburaihan Campus, the University of Tehran in the 2017-2018 crop year. Factors of seedbed planting (stale seedbed and simple), type of living mulch (berseem clover (Trifolium alexandrinum L.), fenugreek (Trigonella foenum-graecum L.) and alfalfa (Medicago sativa L.), planting time of living mulch (two weeks before and at the same time of black seed cultivation). The first factor was in the main plots and the combination of the second and third factors was in the subplots. The results showed that fenugreek and alfalfa were more successful in terms of weed control than clover with a 40% reduction in weed density and biomass compared to the control without live mulch and without weeding. Also, in order to achieve the highest percentage of black cumin yield traits (83.02, 93.44 and 50.50), the number of capsules per plant, number of seeds per capsule and 1000-seed weight, respectively, compared to the control without living mulch and complete weeding, respectively. It is recommended to cultivate fenugreek at the same time as black cumin. In the case of alfalfa, pre-sowing is also recommended. Stale seedbed planting system did not play a positive and significant role in weed control and increase in black seed yield traits.