The current study examined parent heart rate (HR) dynamic changing patterns and their links to observed negative parenting (i.e., emotional unavailability and psychological control) during a parent–child conflict resolution task among 150 parent–child dyads (child age ranged from 6 to 12 years, Mage = 8.54 ± 1.67). Parent HR was obtained from electrocardiogram (ECG) data collected during the parent–child conflict resolution task. Negative parenting was coded offline based on the video recording of the same task. Results revealed that emotionally sensitive parents during the task showed greater HR increases while discussing a conflict and greater HR decreases while resolving the conflict, whereas emotionally unavailable parents showed no changes in HR. However, parent psychological control was not associated with HR dynamics during the task. These findings indicated the physiological underpinnings of parent emotional sensitivity and responsiveness during parent–child interactions. The potential association between HR baseline levels and parenting behaviors was also discussed.