Abstract: The Dual-Slope ADC integrated on chip with has a simple configuration and is suitable to small signal conversion with a low frequency. Based on these characteristics, a programmable Dual-Slope ADC is proposed to convert analog small signal of Magnetic Sensor to digital signal with high-precision. The conversion time and accuracy can be changed freely by different requirement in different application and the resolution of ADC can be programmed, which is beneficial for improving efficiency. In the work, a difference switched-capacitor integrator is used to decrease the area of chip. Besides, the method of integral has been improved. The slope of positive integral can be increased by multiplicity-integral, so the precision of transfer would be raised. Finally,the result of simulation show that the ADC proposed in this paper has a ENOD of 11.96bits and the power consumption with a 3.3V supply is only 1.55mW, which is suitable to detect the small signal output by magnetic sensor in read-out circuit.