Using semantic dependency analysis, this study examines narrative productions from Mandarin-speaking preschool children aged three to six to investigate how semantic organization develops with age in early childhood. Four semantic dependency treebanks were constructed from a Chinese narrative corpus available in the CHILDES database. By comparing semantic dependency types and semantic dependency distances across the four age groups, we found that (1) semantic organization shifted from experiencer and classification relations toward agent and patient relations, situational-role relations (particularly those involving measurement, individuation, and direction), and structural relations; (2) mean semantic dependency distance (MSDD) increased with age, as adjacent dependencies decreased and longer dependencies became more frequent. This increase in MSDD indicates growing complexity in semantic organization and is largely driven by significant increases in the MSDD values of specific semantic dependency types. These findings provide new evidence for semantic organization development in preschool children.