The invention provides a fetal electrocardiosignal self-adaptive blind extraction method based on generalized eigenvalue maximization. The method comprises the following steps: collecting and acquiring blended data including a maternal and fetal electrophysiological signal; based on the self-adaptive real-time algorithm, calculating the covariance matrix characteristic value and characteristic vector of different delayed autocorrelation matrixes within the set period range; selecting the characteristic vector corresponding to the maximum eigenvalue as the blind separation vector so as to extract a fetal electrocardiosignal. The fetal electrocardiosignal self-adaptive blind extraction method utilizes the second-order statistics property of the signal to minimize the noise-to-signal ratio. The second-order statistic method is simple in calculation and small in operation, can still realize effective calculation when the rank of the autocorrelation matrix of the observation vector is close to zero, and can expand to real-time on-line algorithm more conveniently to facilitate product development.