To address the modern breeding demands for high-yield, dense-tolerant, high-quality maize varieties in the mid-maturing region of Jilin Province, the Maize Research Institute of Jilin Academy of Agricultural Sciences bred the new maize variety 'Jidan 427' by crossing the inbred line JiDH1901(female parent) with the inbred line JiDH1200(male parent). From 2019 to 2020, 'Jidan 427' participated in the regional trials and production trials of Jilin Province consecutively. After two years of yield testing, it showed high and stable yields, with an average yield increase of 6.5% compared to the control variety Xianyu 335. The grain bulk density was 748 g/L, with crude protein content of 9.98%, crude fat content of 3.61%, crude starch content of 75.29%, and lysine content of 0.28%. This variety was approved by the Jilin Provincial Crop Variety Approval Committee in 2021(Approval No.: Jishenyu 20210069).