Abstract: The organic content is the main factor of the physical and mechanical properties of turfy soil. Through the characterization study on the organic content of turfy soil as well as its physical and mechanical indexes, the mechanism of mechanical effects resulting from the compression and strength properties of turfy soil with different organic contents is analyzed. The results show that because of the leading role of the porous sponge structure of organic matter and its cementation in the aggregates of turfy soil, the organic matter plays a significantly controlling role both in the relative physical and mechanical indexes and in the mechanical effects. With the increase of organic content, the compressibility of turfy soil rises, the coefficient of consolidation decreases and the permeability goes down, which inserts a great influence on its primary consolidation, and at the same time strengthens the humic cementation of organic matter so as to increase the cohesion. The above property analysis is instructive and meaningful to the solution selection of foundation treatments, and lays the foundation of studying the structure properties of turfy soil as well.