More serious environmental problems including water shortage, wetland degradation, and soil salinization are gradually recognized in the Yellow River Delta wetland. Due to water deficiency of wetland soils, preferential pathways including soil cracks occur as soil shrinkage which changes the hydrological connectivity of inside wetlands or between wetlands at small scale, and small scale hydrological processes tend to affect the large scale hydrological cycle, depending on our urgent needs to restore wetlands, it is necessary to pay attentions to the study of hydrological connectivity research from microcosmic perspectives to promote the understanding of connotation of hydrological connectivity. However, most of the current studies focused on the hydrological connectivity from macroscopical perspectives. In order to clarify the small-scale hydrological connectivity in the Yellow River Delta, the morphology and distribution characteristics of preferential flow in soil were analyzed based on outdoor dyeing tracer experiment and indoor image processing technology. The relationship between preferential flow and soil nutrient content was explored. The results show that:(1) There are two stages in the variation of the dry coverage of Robinia pseudoacacia Linn community with soil depth. The first stage:the interaction between preferential flow and matrix flow is significant; the second stage:the interaction between preferential flow and matrix flow is not significant, and the intensity of preferential flow is gradually increasing, finger flow phenomenon and a small part of pipe flow phenomenon is observed. (2) Vertical soil-profile indexes (dry coverage, dry coverage of preferential pathway, depth of diffusion area, and depth of 50% dry coverage) reveal a strong interaction between preferential flow and matrix flow, and depth of diffusion area occurs in the range of 10-15cm in the soil, which indicates that this type of vegetation community has large depth of water infiltration flow uniformly and the hydrological connectivity is high; (3) The contents of soil organic carbon, organic matter, total nitrogen, total phosphorus and available phosphorus in preferential flow area were higher than those in matrix flow area; (4) The dye coverage ratio of preferential flow area was negatively correlated with the five nutrient indexes, and the contents of organic carbon, organic matter and available phosphorus were significantly affected by preferential pathway. (5) The content of organic carbon, organic matter and available phosphorus in soil can measure the development level of preferential flow to a certain extent. These results can provide references for wetland ecosystem protection and management in the Yellow River Delta.