Based on the digital images of soil aggregates, soil cracks and soil preferential flow patterns in the paddy field, the Image J software was introduced and applied in analyzing soil structural properties in the study. The results indicated that (1) the circularity of soil aggregates in the surface horizon was higher than that of soil clods in the parent material horizon in Pinus massoniana woodland, (2) it is possible to quantify the morphological properties of soil cracks and soil shrinkage curve efficiently through image analysis, (3) dye tracing images in paddy field showed that plough-pan prevented soil preferential flow significantly, moreover, soil pore connectivity varied significantly in the same soil profile. At last the results and the methods of image analysis were discussed also in the paper.