The proposed system is designed to monitor patients with atrial fibrillation (AF) in family. This system mainly consists of wireless sensor networks (WSNs), which contains several mobile sensor nodes and coordinator for acquisition of bio-signals, and an embedded computer (EC) for signal processing. The WSNs are responsible to acquire and transmit Electrocardiogram (ECG). The EC is to extract the AF signal using nonlinear blind source extraction (BSE) algorithm. The extracted AF signal is then utilized to intelligently judge whether or not AF is on, based on which the system will send alert information to related doctors via Ethernet. In the meantime, the extracted AF signal is displayed on liquid crystal display (LCD), and then is also sent to relate doctors. The system aims to be low-cost, low-power consumption, small size and long-distance (up to thirty meters) transmission, can be further integrated into other healthcare monitoring system, and is expected to have great potential in family monitoring.