Abundant research conducted in Western contexts has shown that biological risk factors such as low resting heart rate (HR) might be related to childhood aggression. However, it was unclear (1) how resting HR, as well as other markers of cardiac functions such as resting vagal tone, may be related to subtypes of aggression such as reactive and proactive aggression, and (2) whether the HR-aggression relation can be replicated in non-Western contexts. Therefore, this study examined the concurrent and prospective relations between resting HR, vagal tone, and Chinese children’s reactive and proactive aggression. Participants were 183 children (M age = 7.64 years, 91 girls) recruited from an elementary school in Zhenjiang, PRC. Children’s resting HR and vagal tone were assessed in the second grade (T1). Teachers rated children’s reactive and proactive aggression in the second (T1) and fourth grade (T2). Results showed that lower resting HR at T1 was associated with higher reactive and proactive aggression at T1 and T2, and higher vagal tone was associated with lower HR, which in turn was related to higher reactive and proactive aggression at T1 and T2. Lower vagal tone was directly related to higher reactive but not proactive aggression at T1 and T2, whereas lower HR was related to higher reactive aggression at T2 for children with low or moderate vagal tone but was not for children with high vagal tone. These psychophysiological findings from a non-Western context add additional support for both similarities and differences between reactive and proactive aggression in childhood.