Six current types of A/D converters were introduced, including working principle, circuit structure, performance characteristics and application field. Through analyzing the conversion rate, conversion accuracy, resolution, power consumption, price, size and other indicators, comparing the physical structure design with the actual performance, their appropriate applications were finally summed up. Then, based on the technical characteristics of the existing A/D converters and performance requirements in practical application of the A/D converters, the technology trends of higher performance, lower power and simpler structure on A/D converters are predicted.