The invention discloses a circuit improving dynamic switch linearity in an analog-to-digital converter. The circuit is characterized by comprising a high voltage power generation circuit, a sampling phase clock voltage conversion circuit, and a holding phase clock voltage conversion circuit, wherein the high voltage power generation circuit mainly comprises N voltage boost units that are in parallel connection, each of the sampling phase clock voltage conversion circuit and the holding phase clock voltage conversion circuit comprises M clock voltage conversion units that are in parallel connection, the voltage boost unit mainly comprises seven inverters, two NOR gates, two NAND gates, two buffer units, six NMOS transistors and five capacitors, and the clock voltage conversion unit mainly comprises three PMOS transistors, one NMOS transistor, and a capacitor. The circuit has advantages of improving the performance of a comparator, lowering device imbalance, reducing chip area, loweringswitch power consumption, having strong output and drive capabilities, stable switch signals and so on.