The vegetation concrete ecological base material was selected as the research object, and the samples with six levels of initial water contents of 13%, 19%, 25%, 31%, 37%, 43% were prepared. The dehumidification and humidification processes were simulated by drying method and stacking saturation method respectively. The macroscopic expansion and shrinkage of samples were measured by soil shrinkage meter, and the geometric characteristics of cracks on the surface of samples were extracted by Matlab software. The structural evolution law under the action of drying-wetting cycles was studied. The results show that the drying shrinkage process of the samples at laboratory temperature is manifested as three stages, including sharp shrinkage stage, smooth shrinkage stage and stable stage. During the drying-wetting cycles, the shrinkage and expansion of the samples are almost equal. The crack development process is mainly reflected in the increase of crack width, total length and total area with the increase of cycle times. If the initial water content is too low or too high, the wet expansion and dry shrinkage damage is easily occurred. The average crack width,crack total area, crack length and surface shrinkage of the samples with 31% initial water content are the smallest, which is the optimum water content in production practice.