A water-salt regulation system for coastal regions, including an irrigation canal, a plurality of drainage channels, and a shaft. The irrigation canal is arranged on a surface farmland. The drainage channels are provided inside a soil. The irrigation canal and the drainage channels are inclined from inland to sea. The shaft is provided with a water port at which a sluice gate is provided. An inner peripheral wall of the water drainage channel is provided with a plurality of filter mesh frames with an accommodating cavity. A filter filling material is provided inside the accommodating cavity. The shaft is provided with a salinity sensor. The shaft has a first state with the sluice gate on the drainage channel closed and a second state with the sluice gate on the drainage channel opened. A water-salt regulation is also provided.