An indoor experiment was carried out of having leaf litters from Pinus tabulaeformis and from other 10 species of trees decomposed, separately or mixedly to explore effects of the decomposition on soil properties and any synergic or offsetting actions between the two in mixture. It was found that decomposition of the leaf litters separately significantly increased the activities of soil enzymes, like urease, dehydrogenase and phosphatase, and contents of organic matter and available N, but varied sharply in the effect on available P and CEC in the soil. The decomposition of leaf litter from P. tabulaeformis mixed with that from Platycladus orientalis, Populus simonii, Robinia pseudoacacia, or Ulmus pumila , separately showed obvious synergic effects on total soil microbe. In decomposition, its mixture with that from Hippophae rhamnoides affected activity of the soil enzyme of phosphatase, synergically, but its mixture with the leaf letter from P. orientalis, Betula platyphylla or U. pumila , separately, did reversely. Its mixture with leaf litters from most of the trees, separately, showed a synergic effect on soil available K content, but, reversely on soil available P content. Its mixture with that from P. simonii, H. rhamnoides or Amorpha fruticosa , separately, displayed a synergic effect on soil organic matter content. In terms of soil properties as a whole in their effects, its mixture with leaf litter from H. rhamnoides, R. pseudoacacia, P. simonii or A. fruticosa , separately, all acted synergically, whereas its mixture with that from P. orientalis, Quercus liaotungensis, B. platyphylla, Larix principis-rupprechtii , or Caragana microphylla , separately, did reversely.