Abstract: This paper describes a high precision non-contact physiological signal acquisition system using oversampling technology, which sacrifices sampling rate for achieving a higher accuracy. As we known, due to the low resolution of traditional ADC and the high cost of high- resolution ADC, oversampling technology is used to achieve a high precision data acquisition in this paper. This technology has been remerged to be studied due to its advantage in the acquisition and analysis of weak biomedical signals by using biomedical wireless sensor networks. In this paper, the traditional sampling and the oversampling technologies were compared by quantifying the parameters of signal-to-noise ratio and dynamic range through simulations and experimental measurements. Oversampling technology reduces the quantization noise about 40dB, in other word, the signal-to-noise increases 40dB, which has great improvement in the acquisition system for physiological signals.