Abstract: As the dredged slurry is treated by straw drainage combined with vacuum preloading, the straw drainage will inevitably degrade, thus changing the cultivation performance of the dredged slurry after vacuum preloading. To clarify the influence law of the degradation of straw as a drainage body on the cultivation performance of dredged slurry during vacuum preloading, a large-scale model test of vacuum preloading of dredged slurry with straw as the vertical drainage body is carried out. By measuring the distribution of organic matter and nutrient elements in different positions of dredged slurry after vacuum preloading, the influence of straw drainage body degradation on the cultivability of the dredged slurry is discussed, which can provide technical support for straw drainage used in the ecological treatment of dredged slurry. The results show that compared with untreated dredged slurry, straw degradation would increase the contents of organic matter, carbon（C）, nitrogen（N）, phosphorus（P）, and potassium（K） in the treated slurry, and reduce the carbon nitrogen ratio（C/N）. At the same depth, the organic matter content in the dredged slurry decreases with the increase in the distance from the drainage body. At the same distance from the drainage body, the variation of organic matter content in the dredged slurry with the increase in depth is small, which is less than 1.0%. Additionally, the contents of carbon（C）, nitrogen（N）, phosphorus（P）, and potassium（K） in dredged slurry show different trends with the increase in depth and distance from the drainage body. However, when the distance from the drainage body reaches 30 cm, the content of nutrient elements in the dredged slurry tends to be stable.