Abstract: The dry valley was a typical site of the Baishui River in Jiuzhaigou county, which was also the place where trees were difficultly planted. In this study, afforestation experiments were conducted in 3 aspects, including site preparation, speies selection and watering levels. The results showed that retention rate of saplings in level-terraces group, fish-scale pits group and big planting hole group were significantly higher than control check(CK) group. Based on the analysis, Platycladus orientalis was found to be the best tree-type planted in dry valleys and the descending sequence was Platycladus orientalis, Pistacia chinensis, Pinus tabuliformis and Robinia pseudoacacia. Significant inffluences were also found between watering condition and retention rate of saplings. There was a positive correlation between watering levels and retention rate of sapling. In order to guarantee the effect of afforestation in dry valleys of Jiuzhaigou county, level-terraces or fish-scale pits should be considered in afforestation of dry valley areas, drought-resistant trees like Platycladus orientalis or Pistacia chinensis should also be considered, 2~3 times irrigations could be executed if conditions permitted.