The invention provides a fetus electrocardio separating method and device. The method comprises the steps that an R-wave peak position in a received parent abdominal wall electrocardio signal is adopted as a center locating point, and an electrocardio signal segment with specific length is cut out; the electrocardio signal segment corresponding to the current electrocardio period and the former (M-1) continuous electrocardio signal segments are subjected to linear weighted average, and a recursion template is generated; a parent QRS wave group in the recursion template is subjected to dynamicamplitude correction according to the correlation of a parent RQS wave group in the recursion template and a parent QRS wave group corresponding to the current electrocardio period, and an estimated parent abdominal wall electrocardio signal is generated; the estimated parent abdominal wall electrocardio signal is adopted as a reference signal, the parent abdominal wall electrocardio signal is adopted as an expected signal, and a fetus electrocardio signal is separated from the parent abdominal wall electrocardio signal through an adaptive algorithm. The algorithm is simple, only one parent abdominal wall electrocardio signal is needed, and therefore one-lead fetus electrocardio signal separation can be completed.