The study of incised valleys not only can classify stratigraphy, establish the chronostratigraphic framework, determine the evolution of sedimentary environment, and explore the pattern of sealevel change but also has important significance to the exploration and development of hydrocarbons, and other national economic construction. This paper introduces the concept, characteristics, types, research history and scientific significance of the late Quaternary incised valley system, with the emphasis on the formation, filling evolution of incised valley, sequence stratigraphic framework, the difference between tide and wavedominated incised valley systems, and the controlling factors and comparison of deposition patterns of incised valleys. The late Quaternary incised valley systems are fluvially eroded, elongate palaeotopographic lows developed during episodes of relative sealevel fall, and subsequently infilled and reworked by fluvial, coastal and marine processes during sealevel rise, with the regional stratigraphic unconformability as the bottom boundary. There are many differences between wave and tidedominated incised valley systems: ① the former commonly develop rivermouth bars, central basin and bayhead delta, and the sediments typically exhibit a coarse—fine—coarse grainsize distribution while the latter systems do not develop these sedimentary units, and the sediments present a coarse—fine—coarse—fine grainsize distribution; ② the shallowmarine sediments are thin in the wavedominated incised valley systems but the relatively thick shallowmarine sediments were deposited in the latter systems; ③ the former systems represent sandpoor small river estuaries, which are near the line of maximum transgression due to low mud and sand volume; the latter have stronger fluvial action and relatively high mud and sand volume, thus modern estuaries are constantly expanding seaward, with a much larger extent than incised valleys; ④ the former involve the role of retrogressive accumulation in the filling of incised valleys, but intensities of which are underestimated. Many factors influence the formation and evolution of the incised valley systems, with sealevel change, sediment supply, depositional processes, morphology of incised valley and climate change being the main controlling factors.