Abstract: Based on the field tests, the influences of pile spacing and reinforcement form on the mechanical behavior of pile-supported reinforced embankment are studied. The soil pressures at the top of the pile, the soil stresses between the piles and the deformations of the geogrid at the center line of embankment, 10 m to the right of the center line and shoulder vertical line, are monitored. The variation of stresses of piles and soil, the variation of loads on cross section of subgrade and the deformation laws of geogrid of cross section of subgrade are analyzed. The results show that the critical height of embankment is 1~1.5 times the net spacing of piles. From the embankment center line to the shoulder direction, the stress reduction coefficient increases gradually, and the stress concentration effect decreases gradually. From the embankment center line to the shoulder direction, the deformation of geogrid decreases gradually. The load transfer of pile-supported embankment is mainly based on soil arching effect and supplemented by membrane effect. The test results are compared with the calculated ones of five theoretical methods to evaluate the applicability of the five methods.