Abstract: By using optical microscopic method, the xeromorphism of some important silvicultural species growing in the dry-hot river valley were determined The high root-shooting ratio, thick leaves well-developed palisade tissue and degenerated spongy tissue, the high ratio of palisade tissue to spongy tissue, well-developed water storing tissue, succulence, leaves, isobilateral leaf and thiclk cuticle were important characteristics of xeromorphic structure The role of xeromorphism in drought-resistance was also discussed.