A single-channel fetal electrocardiogram (ECG) monitoring system based on Android mobile smart terminal is designed to realize single-channel fetal ECG extraction algorithm using twice Singular Value Decomposition (SVD), solve the problem of missing waveforms in fetal ECG extraction and obtain real-time fetal ECG signals with high signal-to-noise ratio. Using STM32 single-chip microcomputer to control the 24-bit sampling chip ADS1298, the single-channel pregnant woman's abdomen signal is collected. Then the collected data is transmitted to the mobile intelligent terminal via Bluetooth. On the Android-based mobile smart terminal, the functions of real-time extraction, display, storage and analysis of fetal ECG, calculation of heart rhythm variability, and control of the entire monitoring system are completed. The test results show that the system can accurately extract fetal ECG signals from single-channel pregnant women's abdominal signals, with an improved signal-to-noise ratio of 29.43dB, an accuracy of 98.01%, and a positive prediction rate of 97.81%. The system has good stability and compatibility, and takes about 3.671ms to continuously process 5 maternal cardiac cycles, which is much less than the time of a maternal heartbeat cycle (about 0.8s), and is suitable for maternal or fetal arrhythmia. The fetal ECG monitoring system has the characteristics of simple connection, easy operation, high accuracy, strong portability, etc., and is suitable for primary hospitals and families.