There have been a number of behavioral and neural studies on the processing of syntactic gender and number agreement information, marked by different morpho-syntactic features during sentence comprehension. By using the event-related potential (ERP) technique, the present study investigated whether the processing of semantic gender information and the processing of notional number information can be differentiated and to what extent they might interact during Chinese pronoun resolution. The pronoun (with singular form in Experiment 1 and with plural form in Experiment 2) in a sentence matched its antecedent or mismatched it with respect to either biological gender or notional number or both. While the number mismatch elicited a P600 effect starting from 550 ms (for singular pronoun) or 400 ms (for plural pronoun) post-onset of the pronoun, the gender mismatch elicited an earlier (for singular) and larger (for both singular and plural) P600 effect. More importantly, the double mismatch produced a P600 effect identical to the effect elicited by the single gender mismatch. These results demonstrate that biological gender information and notional number information are processed differentially and have different processing priorities during Chinese pronoun resolution. (Contains 4 tables and 4 figures.)