Ear length is one of yield components and shows higher heritability than that of yield trait in maize. Unlocking its genetic basis is important in order to understand the mechanism of maize yield formation. This study analyzed an ear length major QTL q21EL-GZ that was identified in our research group. The secondary segregation population (BC1F2) harboring the desirable target was used for the genotyping by taking use of the Sequenom SNP technology. The ear length was determined using BC1F2 and derived BC1F2:3 families. The target region containing q21EL-GZ was further narrowed by using the group t test analysis method to a 195-kb interval. Based on the transcriptional profiles, three candidate genes MTD1, RSH2 and APK1B of q21EL-GZ were identified, which would be important targets in gene isolation and functional mechanism analysis.