An indoor experiment was conducted to investigate the characteristics of the unsaturated horizontal infiltration and wetting front advance in cracked yellow cinnamon soil, by incorporating different densities of straws to simulate the different growth stages of crop root, combined with digital image processing and Matlab morphology algorithm. The results showed that the stable forms of soil crack were significantly different in treatments of different straw incorporations（p<0.05）. A downward trend in crack area ratio and crack width (respectively decreased to 1.73% and 0.071cm) was observed with the increasing straw incorporation from 0cm/cm3 to 1.5cm/cm3. Fracture area density and the average crack width of soil stable forms were significantly decreased with straw density increased. The discharge time of horizontal infiltration was affected by the degree of soil cracking. Cumulative infiltration into uncracked soil and cracking soil changed with time was in line with the empirical model proposed by Kostiakov, the parameters of which were closely related to straw densities. The changes of fitting equation reached significant level. The uniformity coefficient of the wetting front was introduced to evaluate the non-uniformity of the horizontal absorption. The initial nonuniformity was more obvious with the increase of soil crack area density and average crack width. The uniformity coefficient was decreased with time. The greater the crack area and the average crack width of soil were, the more obvious the characteristics of nonuniformity in initial stage of infiltration became. According to the changing characteristics of the wetting front forward speed changed with time, the horizontal infiltration process in cracked soils can be divided into three stages: the initial stage of crack flow, the stage of steady matrix flow and the late stage of horizontal infiltration.