Abstract: The relationships among equivalent load,effective stress increment,water content,pore ratio and struccrease.The bigger the water content and the pore ratio are,the lower the structure strength of hydraulic fill is.It is considered that the formation of structure strength of hydraulic fill is closely related to its drainage concretion.The drainage concretion process of hydraulic fill includes forepart air discharge,penetrating concretion in vacuum ture strength were studied to probe the factors influencing the structure strength growth,the result shows that with increasement of effective stress increment and equivalent load,structure strength of hydraulic fill tends to in-seepage field and water gasification discharge under the vacuum condition.