[Objective] Soil macropores in oasis croplands account for a low ratio of the total soil porosity, but significantly influence the path and process of soil water infiltration. Therefore, it is necessary to explore or characterize soil macropores and their effects on the water infiltration process in arid regions.[Method] In this study, we selected three types of oasis croplands(piedmont oasis cropland, old oasis cropland, and marginal oasis cropland), using in-situ dye tracer experiment and a helical medical X-ray computed tomography (CT), the characteristics of soil macropores and water infiltration in the three oasis croplands were quantitatively investigated.[Result] The results showed that soil macropores in the oasis croplands were mainly concentrated in the 0-20 cm soil layer. The three-dimensional macropore structure in the old oasis cropland was more complex than those of piedmont oasis and marginal oasis croplands. Also, the soil macroporosity, fractal dimension, branch density, junction density, and connectivity density in the old oasis cropland were significantly (P<0.05) higher than those of piedmont oasis and marginal oasis. Besides, there was a significant (P<0.05) difference in the steady infiltration rates between the three types of oasis croplands. The steady infiltration rates were of the order marginal oasis cropland (0.48 mm ·min^-1) > old oasis cropland (0.28 mm·min^-1) > piedmont oasis cropland (0.16 mm·min^-1). The dyed area of water infiltration in croplands decreased with the depth of the soil layer. Also, the maximum infiltration depth and preferential flow length index in old oasis cropland were significantly (P<0.05) higher than that in piedmont oasis and marginal oasis croplands, and the degree of preferential flow was also the highest.[Conclusion] In oasis croplands of arid regions, the characteristics of soil macropores are the key factors affecting preferential flow. The oasis soils with high macroporosity and connectivity are more likely to produce preferential flow, resulting in soil water moving to the deep soil layer. It was observed that old oasis cropland had higher macroporosity and pore connectivity than the other oasis croplands, and demonstrated the most obvious degree of preferential flow. This study provides an in-situ measurement technique and database for the study of preferential flow in arid regions.