The effect of reduced nitrogen fertilizer application on trace elements and crop quality in typical lime concretion black soil was studied through long-term straw returning field positioning test. Four treatments were setup:nitrogen，phosphorus and potassiumconventional(N 100PK)，reduced nitrogen fertilizer application by30%(N 70PK)，no nitrogenapplication(N0PK)and nofertilization(CK)under double cropping of wheat and corn with straw returning to the field.The results showed that there was no significant change in the total amount of trace elements in thetopsoil(0-20cm). The avaible Fe content was 8.5-11.0 mg·kg -1，the avaible Mn content was 15.5-19.0 mg·kg -1，the avaible Cu content was 1.6-2.0 mg·kg -1，and the avaible Zn content was extremelylow，ranging from 0.1 to 0.4 mg·kg -1. With the reduction of nitrogenfertilizer application，the content of available Fe and Mn decreased by 26.04% and9.46%，respectively，while there was no significant change in available Cu and Zn. The Cu content in corn grains decreased by 12.5%-24.9% with the reduction ofnitrogen fertilizerapplication，while the Fe content in corn straw decreased by 50.0%-61.4% due to the absence of nitrogenfertilizer application. The Zn content in wheat grains showed a trend of first decreasing and then increasing，while the Fe content in wheat straw decreased by 63.7% to 71.1%. Nitrogen fertilizer reduced corn albumin by 14.0% and wheat prolaminby 25.6%. In conclusion，under the straw returningmode，reducing nitrogen fertilizer application reduced soil available Feand available Mn trace elements and theirbioavailability，and might affect crop quality by inhibiting protein synthesis.