This paper attempts to investigate the repetition of Relative Clauses (RCs) in Mandarin children with Developmental Language Disorder (DLD) (aged 4; 5 to 6; 0) and their typically developing (TD) peers. The results of a sentence repetition task indicate that Mandarin children with DLD perform significantly worse than both groups of TD children, and they tend to make errors involving the relativizer DE and are more likely to produce Non-RC responses. Furthermore, the gap type of RC or the adjective's position does not affect our participants' recall of the test sentences. We conclude that the symmetric performance of our participants in the subject RC and object RC conditions is because the structural intervention occurs in object RCs, but the linear intervention counts more in subject RCs. The syntactic deficit approach better explained the difficulty experienced by children with DLD in RC repetition. Theoretically, this study demonstrates that the Edge Feature Underspecification Hypothesis captures more characteristics of children with DLD in repeating RCs than previous representational theories.