This experiment was conducted on intercropping of onion (Allium cepa L.) with dill (Anethum graveolens L.) at different ridge ratios (sole crop system of each component, 1: 1, 1: 2, 2: 2 and 2: 3 of dill: onion, respectively) combined with different phosphorus fertilization levels (0, 32 and 48 kg P2O5/fed.) during two consecutive winter seasons of 2018/2019 and 2019/2020 at Agricultural Research Farm, Fac. Agric., Zagazig Univ., Sharkia Governorate, Egypt. The study aim was to improve yield components and competitive indices of each crop by using the best treatment of intercropping system in combination with the optimum level of phosphorus fertilizer. The obtained results showed that yield components of dill or onion were significantly affected by intercropping systems. The highest values of fruit and volatile oil yields per dill plant were recorded with 2: 3 intercropping system during both seasons. While, the highest values of onion yield components (grade 1, grade 2, exportable yield, marketable yield and total yield) were achieved by sole crop compared to intercropping systems under study. Land equivalent ratio (LER), area time equivalent ratio (ATER), land utilization efficiency (LUE) with 2: 3 cropping system and phosphorus fertilization level at 32 kg /feddan reached 31.8 and 25.1, 22.1 and 15.8 as well as 26.95 and 20.45 % in the first and second seasons, respectively, compared to the other treatments.. In general, the best combination treatment was 2: 3 system combined with 32 kg P2O5/feddan to improve the yield and maximize the land utilization efficiency.