Abstract In this paper, we address the relation between domain differences and domain adaptation for dependency parsing. Our quantitative analyses showed that it is the inconsistent behavior of same features cross-domain, rather than word or feature coverage, that is the major cause of performances decrease of out-domain model. We further studied those ambiguous features in depth and found that the set of ambiguous features is small and has concentric distributions. Based on the analyses, we proposed a DA method. The DA method can automatically learn which features are ambiguous cross domain according to errors made by out-domain model on in-domain training data. Our method is also extended to utilize multiple out-domain models. The results of dependency parser adaptation from WSJ to Genia and Question bank showed that our method achieved significant improvements on small in-domain datasets where DA is mostly in need. Additionally, we achieved improvement on the published best results of CoNLL07 shared task on domain adaptation, which confirms the significance of our analyses and our method.