Abstract: Based on the large quantities of geological survey materials of Lianyungang area,a series of problems about the soft soil are studied,such as the type of formation cause,the physical characteristics,the indoor experiment,the local experiment and the confirmation of mechanical indexes in particular.The result shows,there are some errors in confirming the mechanical indexes of soft soil by indoor experiment,somtimes the value confirmed by indoor experiment is twice as big as that confirmed by local experiment,which is difficult to handle.Vane test or CPT is suggested to confirm the mechanical indexes of soft soil.