The unique geological conditions lead to the soil preferential flow widely occurs in the karst region. Therefore, in this paper, the typical sugarcane fields in the karst region of Guangxi was taken as study objects, the methods of brilliant blue dye tracer technique and image analysis were used, and the characteristics of soil preferential flows in sugarcane fields were studied under the conventional tillage (CT) and smash-ridging tillage (SRT) in order to reveal the effects of tillage patterns on the occurrence and spatial development of soil preferential flow in sugarcane fields in the karst region. Results showed that: 1) the differentiation degree of preferential flow movement was higher in CT sugarcane field under the same water supply condition. The motion morphology of wetting front in CT sugarcane field was finger form and reached at a depth of 43.19 cm, which was significantly deeper than that of SRT one (P＜0.05). However, the wetting front of preferential flow in SRT sugarcane field was mainly blocky morphology which indicated a horizontal mobility pattern. 2) The occurrence time of preferential flow in SRT sugarcane field was 1.67 times later than that of CT one (P＜0.05). 3) With the increase of soil depth, the preferential flow levels of two tillage patterns both increased first and then decreased. But the preferential flow fraction (70.72%) and length index (527.12%) of SRT sugarcane field were significantly lower than those of CT one (P＜0.05). Meanwhile, the average of variation coefficient of the dyed area percentages in the whole soil profiles in SRT sugarcane field was 1.38 times higher than that of CT one. The degree of preferential flow in SRT sugarcane field was significantly lower than that of CT one. To a certain extent, compared with CT, SRT can reduce the phenomenon of preferential flow and preserve moisture and fertility in sugarcane field of karst region.