Abstract: With the rapid increase of high-risk pregnancy cases in recent years, household on-line fetal monitoring becomes a major issue in the field of perinatally maternal and child care.The fetal electrocardiogram (ECG), which is indirectly recorded from the surface of maternal abdomen, is completely noninvasive, easy to operate and especially suitable for remote household fetal monitoring.However, the signal-to-noise ratio (SNR) of fetal ECG from maternal abdomen is extremely low, and the separation algorithm to extract fetal ECG is very complex.Based on the dynamical modeling in stochastic system and estimation theory, this paper analyzes and studies the basic characteristics of abdominal fetal ECG, makes full use of its dynamical change rule, builds the dynamical space model of abdominal fetal ECG, and puts forward a new kind of low-complexity robust estimation algorithm for single-channel fetal heart rate.Thanks to the simplicity of this algorithm on electrode configuration and its recursion, it is possible for local clients to get online estimation of fetal heart rate, thus is suitable for dynamical monitoring of fetal heart rate at home.