1. A method for bilingual word alignment, comprising: training a bilingual word alignment model using a word-aligned labeled bilingual corpus; word-aligning a plurality of bilingual sentence pairs in a unlabeled bilingual corpus using said bilingual word alignment model; determining whether the word alignment of each of said plurality of bilingual sentence pairs is correct, and if it is correct, adding the bilingual sentence pair into the labeled bilingual corpus and removing the bilingual sentence pair from the unlabeled bilingual corpus; retraining the bilingual word alignment model using the expanded labeled bilingual corpus; and re-word-aligning the remaining bilingual sentence pairs in the unlabeled bilingual corpus using the retrained bilingual word alignment model.