Three experiments on structural priming in Mandarin-speaking 5-year-olds were conducted to test the priming as implicit learning hypothesis. It describes a learning mechanism that acts on a shared abstract syntactic representation in response to linguistic input using an equi-biased Mandarin SVO-"ba" alternation. The first two experiments reported that these children exhibited reliable structural priming in production-to-production and comprehension-to-production using an adult design. A combined analysis of these two experiments suggests the absence of a significant modality effect, indicating that for these children structural priming was guided by a shared abstract syntactic representation. The absence of a significant effect in the magnitudes of structural priming between SVO structural priming and the ba construction suggests that in processing language young children treat "ba" as a function word rather than a content word. Experiment 3 involved 12 presentations of both the SVO structure and the "ba"-construction. Comparisons between Experiments 2 and 3 indicate a cumulative structural priming effect. Further, an inverse-frequency priming effect was found in Experiment 3 for the "ba"-construction but not the SVO structure. Cumulative and inverse-frequency priming effects indicate the learning properties of structural priming. These results support the priming as implicit learning hypothesis that structural priming is supported by a learning mechanism that acts on a shared syntactic representation in response to input.