The yield potential of rapeseed is affected by grass damage，fertilizers，and other factors. Optimizing weed management and phosphorus fertilization play a key role in direct-seeding rapeseed cultivation. A field experiment was conducted in Wuhan，Hubei Province，with two weed management measures（weed-free and weedy）and four phosphorus application levels（P₂O₅ 0，45，90，135 kg·hm^-2 ，represented by P₀，P₄₅，P₉₀ and P₁₃₅，respectively）being set up. The oilseed rape yield，yield components，biomass and nutrient absorption of rapeseed and weeds were measured，and the fertilizer utilization efficiency was analyzed. The results showed that whether weeded or not，the yield of rapeseed treated with P₉₀ was the highest，and compared with no weeding，the yield of rapeseed treated with P₉₀ increased by 66.3% after weeding. Weeding and phosphorus application promoted the yield by increasing the harvest density and the pods per plant. Regardless of weeding or not，the biomass and phosphorus accumulation of rape and weeds increased significantly with the increase of phosphorus application rate in the range of P₂O₅ 90 kg·hm^-2 ，and weeding was more conducive to improving the biomass and phosphorus competitiveness of rape relative to weeds. Compared with no weeding，the proportion of weeds in total biomass after weeding decreased by 58.8%，67.1% and 60.4%，respectively. In addition，the phosphorus accumulation of weeds accounted for 42.0%-62.0% of the total phosphorus accumulation without weeding，and the ratio decreased with the process of growth period after weeding. There was a significant interaction effect between weeding and phosphorus application on the phosphorus fertilizer utilization rate of rapeseed. Compared with no weeding，the phosphorus fertilizer utilization rate of rapeseed after weeding increased by an average of 18.2%. In the rapeseed-weed farmland system，attention needs to be paid to the nutrient absorption of weeds in direct-seeding rapeseed fields. Weeding and phosphorus application could significantly increase the biomass and phosphorus accumulation of rapeseed，increase the proportion of rapeseed in the overall system in terms of phosphorus fertilizer rate，weaken the competitive advantage of weeds in terms of space and nutrient，and effectively improve rapeseed yield and phosphorus fertilizer rate.