As a result of population aging, remote electrocardiograph (ECG) monitoring systems have increasingly gained attention. The traditional ECG signal acquisition system has many limitations. This paper presents a high-precision sigma-delta modulator for ECG signal acquisition. The circuit is implemented in a SMIC-EE 0.18 µm process. Simulation results indicate that the signal-to-noise ratios with and without the SMIC-EE 0.18 µm model are 105 and 81.2 dB, respectively, and the corresponding effect numbers of bits are 17.15 and 13.2 bits, respectively, which meet the requirements of a remote ECG monitoring system.