In order to study the structural change and deformation characteristics of high fill loess under lateral compression, taking the loess of a construction site in Yan’an New Area as the research object, the high-pressure consolidation test of undisturbed and remolded loess was carried out to study the compression characteristics and structural change law of undisturbed and remolded loess under different test conditions. Then the relationship between initial structure, structural yield pressure and compression index were investigated, based on which a modified one-dimensional compression model of loess was established, which was then verified by the test results. The test results show that the changes of moisture and compactness directly affect the initial structure and compression characteristics of the loess, the increase of water content is accompanied by the decrease of structural yield pressure and initial structure, and the increase of compression index. The initial structural parameters change linearly with the structural yield pressure and compression index. With the increase of the compactness, the compression deformation and compression index of the remolded loess decrease, whereas the structural yield pressure and initial structure increase. Under the same moisture content, the initial structural parameters of the undisturbed loess are significantly higher than those of the remolded loess, and the weakening ability of the initial structure of undisturbed loess is much greater than that of remolded loess under the action of humidification. The relationship function of initial structural parameters between undisturbed loess and remolded loess is characterized by the indicators of structural yield pressure and compression index. The calculation model shows that the change of water content gradually reduces the influence of soil compression index and initial structure which increases with the increase of compactness, but has a significant influence on structural yield pressure.