The invention discloses an over-sampling analog to digital converter. The over-sampling analog to digital converter comprises a subtracter, a loop filter, a quantizer and a feedback digital analog converter, which are connected to form a loop, and also comprises an analog dither signal generation circuit, an analog differentiator, a first analog adder and a second analog adder; the analog dither signal generation circuit is used to generate a dither signal containing only noise, and the bandwidth of the dither signal exceeds the sampling frequency of the over-sampling analog to digital converter; the first analog adder is used to add the dither signal to the input of the quantizer; the input port of the analog differentiator is used to receive the dither signal, the transfer function of the analog differentiator is reciprocal to the transfer function of the loop filter, and the analog differentiator is used to perform differential processing on the dither signal; and the second analogadder is used to add the output of the analog differentiator to the output of the feedback digital analog converter. The over-sampling analog to digital converter disclosed by the invention has good linearity; the area and power consumption are also small; and the stability is good.