Objective:Analyzing digital characteristics (chaotic and spectral features) of fetal and pregnant womans Heart Period Signal (HPS) can assess the autonomic function. Methods:Extracting and analyzing HPS of fetal and pregnant woman in perinatal period were realized by the method called visual programming. The hardware consists of electrode, amplifier, analog to digital converter (ADC) with 12bit, printer and microcomputer. Low level I/O operation for the ADC was finished by means of assembler in-line in Delphi (language) under Windows operating system. The software package was designed by Object Oriented Programming technique. So, all the system is a multi-media one and established under Windows. The subjects are in supine,electrocardiosignal (ECS) from the leads placed at symphysis pubica to inferior border of abdominal wall was acquired. ECS was preprocessed by wavelet filter. The sophisticated technique developed by our laboratory was used to accomplish analyzing digital characteristic of HPS. Results: The system could be used to assess fetal and pregnant womans autonomic function, furthermore, sympathetic and parasympathetic nervous function can be evaluated respectively and quantificationally.Discussions:(1) The system could be used to prognosis fetal distress. (2) Digital characteristic of fetal and other age segments HPS that vary with age could approve the viewpoint that there is a characteristic curve to suggest the physiological process of development, mature and senility, based on it, we could find the way of anti-senility. (3) Some digital parameters of fetal HPS locate between those of newborn and adult, which may imply that fetal autonomic nervous regulation is influenced by mothers nerve and endocrine.