This paper proposes a tree kernel method to anaphora resolution of pronouns in both English and Chinese. First, several basic structured tree spans are proposed according to linguistic intuition. The similarity between two structured objects is computed directly using SVMLight. Then, a dynamic-expansion scheme is proposed to automatically determine a proper tree span for pronoun resolution by the centering theory, antecedent competitor-related information, and semantic role-related information. Evaluation on both the ACE 2004 English NWIRE corpus and the ACE 2005 Chinese NWIRE corpus justified the effectiveness of this method.