It is difficult to exactly detect the electric shock current signal of the human body from the leakage current in the residual current protection of low voltage power network. The chaotic system is sensitive to initial conditions and immune noise. Chaotic detection method based on elliptic domain segmentation method is proposed. Elliptic domain segmentation line is introduced in the two-dimensional phase track diagram of chaos system. The state of the phase trajectory passing through the elliptic domain segmentation line is indicated by the high and low level of the output of the elliptic domain segmentation. According to the number of the low level of the output, the state of the chaotic system is determined quantitatively, so as to realize the extraction of the electric shock signal. According to the relationship between the detecting signal phase and chaos system state, the initial phase of the detecting signal is confirmed and corrected to improve the accuracy of the method. The detection results of 195 groups of electric shock signal show that the detection error of the phase corrected before and after is reduced from 32.5% to 4.1%, SNR range detected is increased from [0, -50 dB] to [0, -63 dB]. Simulation results show that this method can detect weak electric shock current in the summation leakage current containing strong noise. The detecting method is of a certain reference value for developing new generation residual current operation devices. This work is supported by National Natural Science Foundation of China (No.51467021).