A Σ-Δ ADC modulator with low voltage and low power consumption is proposed for the application of Σ-Δ ADC in audio equipment. The modulator structure improves the traditional modulator structure and optimizes the modulator coefficients，thus overcoming the shortcomings of the traditional Σ-Δ ADC modulator structure. At the same time，OTA amplifier and comparator，two key circuits in the modulator，are optimized，which greatly improves the performance of OTA amplifier and comparator. The improved modulator has the characteristics of low voltage，low power consumption，high precision and good robustness. The modulator is powered by a 1.2 V low voltage，and it has an over-sampling ratio (OSR) of 128，a sampling frequency of 6.144 MHz，and a signal bandwidth of 20 kHz. Based on SMIC0.11 μm process，the layout design of Σ-Δ ADC modulator was completed，and the streaming chip was finally successful. The measurement results after chip streaming show that the signal-to-noise ratio of the modulator reaches 102.4 dB，the effective bit reaches 16.7 bit，the overall power consumption of the modulator is only about 1.17 mW，and the whole layout area of the modulator is only about 0.122 mm2. The measured performance of the modulator shows that it is a good choice for Σ-Δ ADC circuit in audio chip.