In this study, 5 introgression lines (ILs) and Zong3 were selected to develop segregated populations by Griffing Ⅳ diallel crossing for identifying of QTL for row number per ear and assay of QTL interaction. The SSR markers were used to screen genotype of ILs and F2 individual. In the IL ×Zong3 F2 population, only one QTL for row number per ear was detected in population derived from ILs, with 10.68% phenotypic variation. In populations derived from crossing among ILs, total of 9 QTLs were detected, on chromosome 1, 3 and 8, with 4.53% to 6.52% phenotypic variation. In addition, 2 pairs interactions among QTL, 10 pairs interactions between QTL and introgressed fragment in which QTL did not was detected were found. The sum of phenotypic variation explained by all of interaction pairs was significantly higher than that explained by QTL in each of F2 population. These results indicated that epitasis plays an important role in genetic controlling of row number per ear in maize.