A split-plot field experiment with 2 years old triploid Populus tomentosa clone (B304) as experimental material and diploid clone (1319) as control was conducted in Wei County, Hebei Province. The dynamics of some soil physical-chemical properties in triploid Populus tomentosa plantations during the first four years of cultivation were examined. The results showed that: (1) Both clones′ soil pH increased after planting and the pH value of triploid Populus tomentosa (the mean was 8.43 in 2008) was lower than the control one (the mean was 8.78 in 2008), which was more conductive to soil acid-base balance ability and buffer power. (2) Soil organic matter and available N content first decreased, but then increased in the three soil layers and no significant difference was found between the two clones. (3) After two years of planting, high demand on soil nutrients was found in triploid Populus tomentosa, especially on available P and readily available K whose content decreased significantly in the order of 0-20cm > 20-40cm > 40-60cm. (4) Significant differences caused by year, soil layer and their interaction effect were found for all nutrients′ content and pH value and the same result was also observed for the interaction effect among year, layer and clone.