This study aimed to explore cross-country differences in the characteristics and determinations of self-other risk perceptions of the COVID-19 pandemic. We distinguished perceived risk to self from perceived risk to others and subdivided risk perceptions into three levels: personal, group, and societal. We focused on the differential impact of multiple communication channels (i.e., interpersonal communication, traditional media exposure, and new media exposure) on risk perceptions at the three levels. A sample of 790 college students completed self-report online questionnaires from May to June 2020, including 498 in China and 292 in the United States. The results showed an "ascending pattern," revealing that participants perceived higher levels of risk to others than to themselves. In addition, U.S. college students perceived higher risks of COVID-19 than Chinese college students at all levels. As for the relations between communication and risk perceptions, the results revealed that interpersonal communication and traditional media exposure were more effective with Chinese participants, whereas new media exposure was more effective with U.S. participants. Specifically, interpersonal communication was positively associated with risk perceptions at three levels, and the magnitude of the effect was higher in the Chinese group than in the U.S. group. Traditional media exposure increased societal risk perception only for Chinese college students, and new media exposure increased societal risk perception only for U.S. college students. Our findings provide theoretical implications for the characteristics and forming mechanisms of risk perceptions and also provide practical implications for policymakers in the two countries to implement effective measures to foster individuals' risk perceptions in relation to preventive behaviors.