Dependency distance, regarded as a measure of syntactic complexity, can be used to establish the relationship between textual factors and cognitive effort in language processing. Psycholinguistic studies have found that disfluency is related to cognitive states and processes, and can be used as a measure of behavior to assess the cognitive load of interpreting tasks. This study examines the effects of the maximum dependency distance of the original text on the disfluencies of the sight interpreting and moderating effect of syntactic structures between the two parties. Results show that the number of disfluencies of the sentences with the longest dependency distance in the long group is significantly higher than the sentences in the shortest group with the longest dependency distance, but the degree of difference varies in different syntactic structures. This study proves that dependency distance can be used to measure and predict the cognitive load and difficulty of interpreting tasks.