In order to explore the effect of reduced nitrogen fertilizer application on mixed forage yield and silage quality under the silage maize and leguminous green manure intercropping system in the Loess Plateau of Shanxi Province，four silage maize and leguminous green manure intercropping treatments(A1:maize monoculture；A2:maize + Mulu 9；A3:maize + Mulu 2；A4:maize + laba bean)，and four nitrogen gradients(B1:100%N；B2:90%N；B3:80%N；B4:70%N)were set up，in which nitrogen fertilizer was applied normally in the first year and reduced nitrogen fertilizer was applied in the second year. The fresh grass yield and nutrient content of the forage mixture were measured at the harvest time of silage maize. The results showed that intercropping green manure increased the yield of mixed forage and increased the contents of crude protein，crude fat，crude ash and starch in silage forage at the same nitrogen application level. Reduced nitrogen fertilizer application reduced the yield and quality of mixed forage，and reduced the contents of crude protein，crude fat，crude ash and starch in silage. Intercropping green manure could replace 10% nitrogen fertilizer application rate，and the treatment of intercropping Laba bean with 90% nitrogen fertilizer had the best effect.