This mixed-method study explored academics' beliefs about interdisciplinary research collaboration (IDRC) and their influences on collaborative practices in a Chinese research university. Exploratory interviews with nine academics were first conducted to examine their beliefs about IDRC. The findings revealed that the academics' beliefs about IDRC fell into six broad themes, that is, IDRC: helps better address research problems; helps achieve innovative results; helps expand new academic fields; is challenging which requires crossing boundaries among disciplines; is a gradual process that takes plenty of time and effort; and is not necessary as some research problems can be addressed through within-disciplinary research. Based on the interview findings, a questionnaire was developed to examine the influences of academics' beliefs about IDRC on their self-reported collaborative practices and then administered to 659 academics in the university. Results showed that four of the six beliefs significantly and positively affected self-reported collaborative practice; one belief significantly and negatively affected self-reported collaborative practice; and one belief had no significant effect on self-reported collaborative practice. Differences existed among the academics of different disciplines regarding the influence of their beliefs about IDRC on self-reported collaborative practice. The practical implications of the findings and suggestions for future research are discussed.