By seismic reflection interpretation，stratigraphic correlation and study on parasequence sets and relative lakelevel changes，the differences in sandbody distribution patterns were proposed for the1st member of lower Cretaceous Duhongmu Formation in Baiyinchagan sag. The results show that during the sedimentary period of the 1st member of Duhongmu Formation，the relative lakelevel changes are different in different areas of the basin，different types of parasequencesets in one systems tract are resulted in. The seismic reflection features is different obviously in different part of the 1st member of Duhongmu Formation. The seismic reflection frequency is medium high and the amplitude is moderate and continuous in Xilinhaolai area of southwester gentle slope belt of Baiyinchagan sag，and the formations prograde towards the north layer by layer. But the frequency is low，and amplitude is weak with poor continuity，and the formations retrograde layer by layer in Daerqi area of north eastern gentle slope. When the 1st member of Duhongmu Formation deposited，the provenance was sufficient in the Xilinhaolai area，and thus the fan scale was relatively large and its granularity was coarser with coarsing upwards. Progressive delta sand body developed in the whole area and the progressive parasequence sets were formed in Xilinhaolai area. But in northern steep slope zone of Daerqi area，the provenance supply was poor and the relative lake level ascended，and thus the regressive delta sand body developed and parasequence sets were formed under the progressive lake background. There is a trade-off relationship in the development of sandbodies between westsouth Xilinhaolai area and northeast Daerqi area.