The utility model provides a freezing-melting circulation detecting device suitable for natural saline soils and used for detecting the forming process of the saline soils under a natural environmental condition and detecting the change rule of frost heaving and melt sinking in a multi-time freezing-melting circulation process. The freezing-melting circulation detecting device is characterized in that the upper part of a sample barrel of the device is connected with a low-temperature constant-temperature box for the temperature change under a natural state, and the setting the common temperature is determined according to the air temperature of the region; the bottom of the sample barrel is also fixedly provided with a temperature controlling head for detecting the temperatures among soil bodies under the natural condition, and the temperature is generally set at + 5 DEG C; the temperature controlling head arranged on the bottom of the sample barrel is connected with a water replenishing device for detecting the replenishment of the underground water and the salinity under the natural condition. The freezing-melting circulation detecting device suitable for the natural saline soils provided by the utility model has the advantages that a freezing-melting circulation mechanism of the saline soils is well reflected, and the reference is provided for the engineering construction of a saline soil region.