Dependency is dynamic manifestation of valency, and dependency distance (DD) is closely related to syntactic structure. By introducing the concept degree in graph theory, we analyze the relationship between dynamic valency (DV) and DD based on the Chinese and English treebanks. Our findings are: (1) the mean dependency distance (MDD) of the Chinese treebank is greater than that of English, while the variance of DV of Chinese is lower than that of English; (2) some values of the variance of DV exist in Chinese but not in English; (3) at a specific sentence length, there is a linear relationship between MDD and the variance of DV in the syntactic structures in English and Chinese. These findings suggest: (1) Chinese may have some unique syntactic dependency structures that are not found in English; (2) high DV may contribute to high MDD, but this effect on MDD may not be stronger than some grammatical factors.