A gas purification system with a water tank, a reaction cavity, a condensation trap device and a dust collection chamber is disclosed. The reaction cavity uses a negative pressure suction to transport a water vapor and a gas to be processed into the reaction cavity, the gas to be processed at least contains a waste gas that can react with the water vapor, so that the water vapor contacts the waste gas in the gas to be processed and performs a reaction to obtain at least one product. The condensation trap device performs a condensation capture processing and a centrifugal separation processing on the product. The dust collection chamber is used to collect the product thrown out by centrifugal force and/or dropped by gravity.