On the basis of clarifying that intercropping crops can improve nitrogen absorption and utilization，the intercropping system nitrogen interspecific relationship and the contribution of related environmental factors were discussed，which provided certain data support for clarifying the nutrient utilization advantages of intercropping. In this study，through a two-year field trial(2021—2023)under four nitrogen application levels no nitrogen(N0)，low nitrogen(N1，90 kg/hm²)，conventional nitrogen(N2，180 kg/hm²)，high nitrogen(N3，270 kg/hm²)，the effects of wheat and faba bean intercropping on nitrogen harvest index，system nitrogen productivity and nitrogen interspecific interaction，and contribution on intercropping to promote nitrogen absorption and utilization combined with related environmental factors was comprehensively discussed based on the analysis of aggregated boosted tree(ABT)and network. The results showed as follow:Compared with monocropped treatment，the nitrogen harvest index of intercropped wheat increased by an average of 5.30% in two years，and intercropped faba bean was significantly increased by 15.55%. The nitrogen system production of intercropping system reached 66.47 kg/hm² on average. Both wheat and faba bean showed different degrees of nitrogen interspecific competition，and their relative interspecific competition intensity was -0.83 and -0.73，respectively，the range of nitrogen relative interspecific competitiveness were 0.087-0.11(wheat)and 0.047-0.12(faba bean)，showing different degrees of interspecific complementation. Compared with faba bean，the nitrogen relative interspecific competitiveness of intercropped wheat reached an average of 0.43，showing obvious interspecific competitive advantages. In terms of contribution rate on nitrogen harvest index of soil environmental factors and nitrogen interspecific relationship indicators，the first contributing factors of monocropped wheat and faba bean were both available potassium and nitrogen relative interspecific competition intensity，the first contributing factor of intercropped wheat was alkali hydrolyzable nitrogen and relative interspecific competitiveness of nitrogen，intercropped faba bean was alkali hydrolyzable nitrogen and the relative intensity of nitrogen competition. Wheat and faba bean intercropping could improve the nitrogen harvest index，maintain the nitrogen interspecific complementation and the nitrogen competitive advantage of wheat while nitrogen competing for crop species，and improve the contribution of soil available nitrogen and the relative interaction index of nitrogen，stabilize the nitrogen system productivity of the intercropping system and the advantages of nitrogen absorption and utilization.