The invention relates to a test device for clogging characteristic of a geotechnical synthetic material. The test device is applied to a clogging experiment for geotextiles in a pressure bearing state and comprises a base, a supporting tube, a supporting plate, a penetration tube, a water head lift mechanism, a pressurizing device and a pressure measurement assembly; the supporting tube is fixedly arranged on the base in a sealed manner; the supporting tube is provided with a drainage opening and a first detecting hole in the radial direction; the supporting plate is fixedly arranged on the top of the supporting tube in a sealed manner and is provided with a plurality of through holes; the penetration tube is fixedly arranged on the supporting tube in a sealed manner and is provided with five detecting holes in the radial direction; the pressure measurement assembly is used for detecting five water pressure difference values between the first detecting hole and the five detecting holes; the water head lift mechanism can be used for changing the water head difference of the test device; the pressurizing device is used for applying pressure to an experimental soil sample in the penetration tube. According to the device, set pressure can be applied to a fabric sample, a gradient ratio and the content of soil in the sample can be accurately obtained, and then, the clogging characteristic of the fabric sample is accurately evaluated.