Dry jet mixing (DJM) piles are widely used in silt foundation treatment to improve foundation stability and control post-construction deformation. As the work mechanism of DJM composite foundation is very complex, though many useful calculation theories have achieved, the theoretical study of DJM pile composite foundation is still far behind engineering practice, the settlement and stress calculation precision is unsatisfied. Then it is still necessary to reveal the work mechanism of DJM pile comprehensively. A field test of DJM pile composite road foundation is carried out and many measurement methods are adopt to collect the test information, such as soil pressure sensors, pore pressure sensors, settlement plates, inclinometer tubes, stratified settlement pipes, multi-point displacement meters in piles and so on. Then the surface settlement, internal deformation and stress developing of soils and piles are monitored Real-time. Through in-site test, the settlement and internal deformation of piles and soils, the stress ratio between pile and soil, and the negative friction around pile are studied.