The invention discloses a processing method and a system of radioactive chemical wastewater in nuclear power plants, including the following steps: heat and dry the radioactive chemical wastewater; separate the wastewater into salt particles and gas with dust; use a dust remover to separate the gas into salt particles and exhaust gas; collect these salt particles to make into waste drum; filter the gas using a high-efficiency particulate air filter; exhaust the rest gas to atmosphere after passing test and perform the processing of chemical wastewater. Compared to existing technologies, the processing method of chemical wastewater has advantages of simple system configuration, high processing efficiency, non-secondary wastewater and high volume reduction factor. The generated secondary solid waste meets the requirement of waste package and waste disposal sites after effective packing. In addition to these advantages, the processing method also provides a processing system of radioactive chemical wastewater in nuclear power plants.