  Due to the ambiguity of homophones, Chinese Spell Checking (CSC) has
widespread applications. Existing systems typically utilize BERT for text
encoding. However, CSC requires the model to account for both phonetic and
graphemic information. To adapt BERT to the CSC task, we propose a token-level
self-distillation contrastive learning method. We employ BERT to encode both
the corrupted and corresponding correct sentence. Then, we use contrastive
learning loss to regularize corrupted tokens' hidden states to be closer to
counterparts in the correct sentence. On three CSC datasets, we confirmed our
method provides a significant improvement above baselines.
