Building on the description of acoustic patterns of neutral tone produced by Mandarin-speaking adults in literature and the corresponding proposals of phonological-phonetic mapping mechanism, the present study examined the production of two consecutive neutral tones by Mandarin-speaking preschool children. Data was extracted from spontaneous conversation between preschoolers and their caretakers in CASS-CHILD, a child language corpus of Mandarin-speaking children. Results show the developmental process of consecutive tones production in terms of F0 contour, pitch range, and duration. Our findings are in accord with established research on the early mastery of tone features and synchronous development among lexical tone categories in prosody acquisition. Furthermore, it is revealed from this study that preschoolers perform well on acquiring phonological representation of neutral tone and sandhi. Even so, they may have difficulties in accurately realizing consecutive neutral tones in the following conditions: 1) when the preceding full syllable is Tone 2 or Tone 3, which in themselves trouble young speakers; 2) when word prosody interacts with phrase-level prosody, for example, domain-final lengthening at intonational phrase boundaries. In addition, acoustic parameters, pitch and duration in our case, interfere one another in preschoolers' off-standard realization of consecutive neutral tones.