Dry matter accumulation (DMA) is the basis of maize (Zea mays L.) grain production. In order to investigate the traits related to DMA before and after flowering of maize, experiments were conducted on maize cultivars released from the 1950s to the 2010s, which were grown at densities of 37,500 and 82,500 plants ha^–1. In improved cultivars, the contribution of total DMA (54% – 88%) to grain yield gain was greater than the contribution of harvest index (HI) (12% – 46%). A significant increase in total DMA for maize cultivars resulted from increase in DMA during the reproductive stage (DMAR) and DMAR rates. Leaf area index at anthesis or dent stage and the staygreen index significantly increased. Leaf area duration was greater for new cultivars than for old ones, both before and after anthesis. These traits could be selected for by maize breeders to improve DMA, thus increase maize grain yield in China.