Flowering time is an indicator of adaptation in maize and a key trait for selection in breeding. The genetic basis offlowering time in maize, especially in response to plant density, remains unclear. The objective of this study was to identify maize quantitative trait loci (QTL) associated withflowering time-related traits that are stably expressed under several plant densities and show additive effects that vary with plant density. Three hundred recombinant inbred lines (RIL) derived from a cross between Ye 478 and Qi 319, together with their parents, were planted at three plant densities (90,000, 120,000, and 150,000 plants ha-1) in four environments. Thefive traits investigated were days to tasseling (DTT), days to silking (DTS), days to pollen shed (DTP), interval between anthesis and silking (ASI), and interval between tas-seling and anthesis (TAI). A high-resolution bin map was used for QTL mapping. In the RIL population, the DTT, DTS, and DTP values increased with plant density, whereas the ASI and TAI values showed neg-ligible response to plant density. A total of 72 QTL were identified for flowering time-related traits, including 15 stably expressed across environments. Maizeflowering time under different densities seems to be regulated by complex pathways rather than by several major genes or an independent pathway. The effects of some stable QTL, especially qDTT8-1 and qDTT10-4, varied with plant density. Fine mapping and cloning of these QTL will shed light on the mechanism of flowering time and assist in breeding early-maturing maize inbred lines and hybrids.