Abstract: In order to explore the application effect of grass cultivation technology in tobacco fields, Astragalus sinicus, Trifolium repens and Trifolium pratense were selected as experimental plants to study their weed control effects, as well as their effects on the agronomic traits of tobacco and the yield, output value and chemical components of tobacco leaves, and the results showed that their extracts had strong inhibitory effects on the germination of Setaria viridis and Chenopodium album, the dominant weeds in tobacco fields of Tongren, and grass cultivation significantly improved soil fertility. The weed control efficacy of the grass cultivation in tobacco fields increased with the rise in grass seed sowing rate. The treatment with Trifolium pratense (150 kg/ha) showed the highest efficacy, with a plant control efficacy of 78.32% and a fresh weight control efficacy of 86.38% 60 days after sowing. Compared with tobacco fields with naturally grown weeds, the grass cultivation improved the agronomic traits of tobacco plants, with increased or significantly increased leaf length, leaf width, stem circumference and effective leaf number. The yield and output value of tobacco leaves treated with the grass cultivation increased by 124.21%-209.70% and 260.44%-433.42%, respectively, while the proportion of high-quality tobacco leaves and the average price increased by 380.88%-823.32% and 50.13%-83.13%, respectively. Compared with tobacco fields with manual weeding, the agronomic trait indexes of tobacco plants under the various grass cultivation treatments, such as leaf length, leaf width and stem circumference were slightly reduced. The yield and output value of Trifolium pratense (150 kg/ha) treatment increased by 2.17% and 9.97%, respectively. The indexes of total nitrogen, nicotine, potassium ion, chloride ion, potassium-chloride ratio and sugar-alkaloid ratio in tobacco leaves treated with the grass cultivation generally met the requirements for high-quality tobacco leaves.