The soil salinization degree of coastal shoal is high in China, which is one of soil ecological environment problems attracting much attention. The rules of soil water and salt migration are the theoretical foundation of improving the soil salinization. Based on the static soil salt migration test and indoor one-dimensional soil column test, mucky clay in coastal shoal was studied, and the migration pattern and mechanism of salt in mucky clay were analyzed. Results show that under the static state, the migration velocity and migration rate of salt are positively correlated with water volume in the same time. Under the condition of one-dimensional hydrodynamic dispersion, the migration velocity and migration rate of salt increase with the hydraulic gradient and the hydrodynamic dispersion.