Abstract: Mental activities can increase the incidence of malignant arrhythmia. Two different mental task projects, i.e. mathematical task and control of heart rate task, are designed to study the changes of cardiac function. The spectral coherence is used to analyze the coupling of electroencephalogram (EEG) and electrocardiograph (ECG). The results demonstrated that pre-central and post-central areas were participated in the information exchange of the heart during the mathematic task, while the information coupling between heart and brain for controlling heart rate task mainly concentrated in the central and pre-central areas.