Priming studies with adult readers have provided evidence for the activation of morpho-semantics during the processing of words with the appearance of morphological complexity. The present studies investigated whether evidence for the effects of morpho-semantics can be obtained with developing readers. Chinese third, fifth graders and adults (the latter as a control group) performed lexical decision tasks in which opaque and transparent words were primes and targets to each other. There are still the other two control conditions, in which both opaque and transparent targets were preceded by the form and morphological unrelated control words. Results showed that across all groups, when primes and targets share the same morphemes, the correct rate of the transparent words was significant higher than that of the opaque words; but when primes and targets had no such relationship, participants responded more quickly and accurately to the opaque words. This pattern of results indicates that morpho-semantics could play an important role even in developing readers.