The Coefficient of earth pressure at rest K0 is an important parameter for solving geotechnical engineering problems. In order to study the influencing factors and mechanisms of peat soil K0, a K0 consolidation instrument was used to conduct a lateral compression test on Kunming Dianchi peat soil. The effects of vertical stress, organic matter content and initial void ratio on K0 were systematically analyzed, and from the structural perspective Starting from the perspective, we explore the formation mechanism of its K0 change law. The test results show that the Coefficient of earth pressure at rest of reshaped peat soil is not a constant, but is related to the vertical stress and organic matter content; K0 decreases with the increase of vertical stress during loading and finally tends to be stable. The decreasing trend of K0 under stress is more significant; under the same vertical stress, the greater the organic matter content of the soil sample, the smaller K0, and the greater the decrease in K0 during the entire loading process; the dynamic changes in the structural properties of peat soil during the loading process are the fundamental cause of changes in K0. Vertical stress and organic matter affect K0 by affecting its structural properties, and there is a certain coupling relationship between the two; the K0 value after stabilization of reshaped peat soil is between 0.42 and 0.6, which is lower than that of inorganic clay, and has a linear negative correlation with the organic matter content. Based on the experimental results, a corresponding fitting relationship is proposed; the relationship between the initial void ratio and the K0 value is relatively discrete.