Abstract: The purpose of the research is to analyze the stability of the Lanshayang Channel. As a tidal channel, the Lanshayang Channel is located in the south part of the radial sand ridge field of the Yellow Sea. It was proposed to be the candidate location for a harbor. Previous research has shown that the radial sand ridge field has been stable for thousands years. However, few researches have been carried out directly on the stability of the Lanshayang Channel itself, which is, by all means of, the fundamental pre-condition for the harbor construction. To understand the local evolution history during the past thousand years we studied the sedimentology, paleontology, and chronology of three cores (A, B, C) collected across the Lanshayang Channel.Results from Core A and B show that during the past thousand years, the area of these cores has been stable, with very little siltation rate (Core A 4.00~4.67mm/a and Core B 2.16mm/a). Coccolith abundance also shows that the ancient water depthes are around 10m or less at both sites of core A and B, which coincides with the current water depth. Results of Core C are however more complicated. Core C is located at the bottom of this channel, with current water depth around 18m. As this place was designed to be the harbor pool site, the stability of this area is extremely important for the construction of the harbor. The upper part of Core C, about 12m in thickness is unexpectedly characterized by some convolute bedding and disturbed bedding, which might possibly be caused by earthquakes or storm surges. The coccolith abundance shows that the ancient water depth of this upper part is around 10m, but of the lower part over 20m.In order to resolve this problem, charts of this area drawn in different years (1992, 1994 and 2003) were analyzed by GIS. The analysis reveals that in the past decade, water depth of this area has been changed from 30m to 18m, which supports the following assumptions: The upper part of Core C was formed in the past decade. Its water depth has been kept over 18m, but with sediments from shallower water nearby, which was associated with some events (earthquakes or storm surges). GIS analysis also shows that erosion and siltation in the whole research area keeps good balance. Based on these conclusions we suggest that for harbor construction in this area, engineering approaches must be strongly emphasized in order to reduce the impacts of certain events and to minimize the siltation in designed harbor pool area.