A system for locating the existence of a biventricular pace pulse for ECG, which includes a non-biventricular pulse detector for finding the onsets of ventricular pulses, a lead-wise biventricular pulse detector for checking whether there are two separated ventricular pulses in one heartbeat, and a vector-based biventricular pulse detector for determining the existence of the biventricular pace pulse if the lead-wise biventricular pulse detector does not find that there are two separated ventricular pulses in one heartbeat.