A cDNA library was constructed and characterized from the pulp of Cara Cara navel orange (Citrus sinensis Osbeck) at different stages of ripening. Tittering results revealed that approximately 5.086x105 independent clones were included in this library. Electrophoresis gel results of 15 randomly selected clones revealed that the size of the insertion fragments ranged from 400 bp to 2 kb, with an average size of 900 bp. Sequencing results of 150 randomly picked clones showed that the recombination rate was 94%. During subsequent sequence analysis, 41 of 139 clones failed to be identified and the amino sequence of 71 clones shared less than 30% identity with related plants in GenBank. Of 27 clones whose amino sequences shared more than 60% identity with other related plants in GenBank, 17 clones showed an 80% identity with the corresponding candidate genes of citrus. The clone recognized as the type Ⅲ metallothionein-like (MT) gene was observed to occur 13 times, indicating that the protein may play an important role in fruit development and ripening.