Abstract: In the study，we used the elite inbred line Nongxi531（ NX531） and the space mutation inbred line Nongxi531（ M-NX531） as the parents to building F2∶3 populations to investigating the bulk density traits，and planted the parents and F2:3 populations in Handan academy of agricultural sciences in the summer of 2012，and measured bulk density traits after harvesting. Using the SSR marker to constructed the genetic map of this population. Used the complete complex interval mapping method（ ICIM） for QTL mapping，and evaluated the additive and epistatic effects of QTLs. The results showed that the total length of the genetic map was 1 179.8 cM，which occupied 85.76% of the whole maize genome，and the average distance between the markers was 11.91 cM. We detected 3 additive QTLs through the QTL mapping analysis，which were located on 1st，6th，8th chromosomes，and explained 20.29%phenotypic variation；detected 3 epistatic QTLs，which involving 6 sites，located in 1st，3th，4th and 10th chromosomes，expanded the phenotypic variation in 67.08%. These results indicated that except the additive and dominant effects，epistasis effect was also an important genetic basis for bulk density of maize.