It is a fundamental task for soil structure study to find a quantitative parameter that reflects structural damage under pressure. Based on the unidirectional compression and isotonic compression tests of soft clays from Huangshi, Zhangzhou and Qingdao, the compression properties of structure soil and the effect of different conditions on the properties were investigated. It is found that when the pressure is lower than structure yield stress, it is mainly the initial structure selfalignment procedure and the structure is in few damage and the compressibility is small. When the pressure is bigger than the structure yield pressure, the structure destroys massively and the compressibility increases greatly not only from intergranular slipping but also from the collapse. With the damage properties in compression, a new coefficient was proposed to evaluate the structural behavior. And this parameter can be obtained simply through the software AutoCAD. With the proposed method, it is found that the soft clay in Qingdao is strongest in structural behavior, followed with that in Huangshi and Zhangzhou.