Abstract: In this paper, we provided a design of an in-situ monitoring system for seabed erosion and deposition based on resistivity, which may carry out long distance automatic monitoring in a water depth of a few meters. It uses two kinds of data storage and transmission mode, i.e. the USB mass storage technology and GPRS wireless communication, to achieve long-term unattended in-situ monitoring. Utilization of the different resistivity between seawater and seabed sediments, an electrode probe rod layout spacing ring is imbedded into the seabed, and continuous testing resistivity around the seawater and seabed sediment interface up to a certain level, of which the change in interval electricity is large enough. And then use the appropriate method to determine the accurate interface position. The interface position changes with time, up to the change in seabed erosion and deposition. Laboratory experiments show that the tested erosion and deposition data conforms well to the actual data during deposition process, and the maximum error between the two kinds of data is less than 0.3cm. At present, the system can effectively work in shallow beach area (a few meters of water depth) for automatic in situ monitoring of seabed erosion and deposition.