Study on secondary consolidation characteristics and mechanism of structured loess has become an effective means of calculating and controlling post-construction settlement in loess high fill foundation. In this paper, the secondary consolidation characteristics and deformation mechanism are studied by means of compression test of structured loess. Then the formula describing the time effect of secondary settlement coefficient is established. The test results show that an obvious secondary-consolidation effect exists in structured loess. The load coefficient of secondary consolidation curve(P-Cα)increases first and then decreases, and it finally tends to be stable. The peak of Cα corresponding to the loading value is greater than Pc. High stress loads are not major controlling factor of the secondary consolidation coefficient. The influence mechanism of load and water content on secondary settlement coefficient is analyzed based on geotechnical mechanics. The P-Cα curve of structured loess in high water content only decreases and tends to be a stable period by weakening effect of water on soil particles. Establishing the formula describing the time effect of secondary settlement coefficient can provide help for post-construction calculation of the covered original loess foundation in high fill engineering.