Abstract: In order to investigate the amount of nitrogen and phosphorus used for forage rape（Brassica napus） production, the effects of nitrogen and phosphorus application on growth traits and yield of forage rape multiple corpping after wheat were studied. Huayouza 62 was used as the experimental material,and a two-factor three-level randomized block design was used to set three levels of nitrogen application（N1=75 kg/hm²,N2=150 kg/hm²,N3=225 kg/hm²）,3 levels of phosphorus application（P1=60 kg/hm², P2=120 kg/hm², P3=180 kg/hm²）. The results showed that,when the nitrogen application rate was 150~225 kg/hm²,the agronomic traits and yield of the forage rape were significantly improved. The effects of different phosphorus application rates on the agronomic traits and yield of forage rape were not significant. Different combinations of nitrogen and phosphorus had significant effects on biological yield and fertilizer economic benefits of forage rape. N2P1 treatment yield reached 94 016 kg/hm²,and the highest ratio of production to investment （12.68）;N2P2 had the highest yield of forage rape （100 832 kg/hm²）,yield ratio centered,with the highest net income. Therefore,the application of N 150 kg/hm²,P 120 kg/hm² fertilizer in the growth period of the forage rape could make the forage rape obtain high yield,save the fertilizer cost,and increase the economic benefits.

Key words: nitrogen and phosphorus combined application, growth traits, forage rape（Brassica napus）, yield