Aiming at the high imbalance, low stability of the standard voltage source, the implement scheme of a high precision voltage source was put forward in this paper. The 20 bit high precision analog-to-digital converter AD5791 was selected through analyzing the requirement of the digital-to-analog converter for the generation process of the standard voltage source reference voltage source. The design scheme of the circuit was presented and the high imbalance phenomenon of the past D/A converters as a reference source was overcome by combining the AD5791 hardware features and software settings. The test of the experimental data showed that the proposed scheme had advantages of high linearity and good stability. The 0~10 V continuous voltage can be output with the precision of 0.02 mV, and the linearity is up to 99.996%. It can satisfy the design requirements of high precision voltage source.