In this study, a constant head infiltration device was used to investigate the distribution characteristics of one- dimensional vertical infiltration water and salt in layered saline and alkaline soil with a subsurface straw layer at a depth of 20 cm below soil surface. Four levels, 0 (CK), 6 000, 12 000, and 18 000 kg/hm2, of straw amount with 2 levels, 1 and 10 cm, of straw length were set up to investigate their influences on the distribution of infiltration water and salt in saline alkaline soil. The results showed that the subsurface straw layer in saline alkaline soil clearly lowered water infiltration with apparent drops in accumulated infiltration amount and infiltration rate. And infiltration water stopped above the straw layer within certain limits. At the same time, the subsurface straw layer prevented water from going through, resulting in an obvious decrease of water below it. Salt content peaked at a certain depth below the straw layer. And straw length exerted an effect on the depth where salts were stopped with the peak of the total salt content at a deeper position in the 10 cm straw length treatments compared with that in the 1 cm treatments. The subsurface straw layer also impacted the ion exchange and adsorption during water infiltration. The changes of Cl– distribution in the soil profile after infiltration was similar to that of total salt. HCO3– was obviously more sensitive to the subsurface straw layer than SO42– which relied heavily on water and only migrated rapidly when water content was high enough.