Abstract：When dike reinforcement with silt was applied in Yellow River，cracks appeared in the first stage project in Henan and Shandong Province. Because of the particularity for the dike reinforcement with silt，there was no quantitative result of the effect of crack on safety of dike，and safety features of dike were not clarified under the work of crack so that it would be restricted to prepare treatment and counter plan of contingency. When dilapidation or crack occurred in dike，the safety status was influenced by factors including status of crack，water level，rainfall，characteristic of soil and so on. Taking the Dongming dike-section of Yellow River in Shandong Province as an example，endanger of crack on safety of dike was analyzed. It shows that the deeper the depth of crack is，the lower the safe of dike is，and the safety of status of dike becomes abominable with rainfall. Moreover，the damage degree of crack of dike is closely correlated with the characteristic of soil，and the chance of accident is proportional to the rainfall duration，intension of rainfall，depth of crack，decreasing velocity of water level of the dike in nearby river. The results could be applicable as reference in flood control emergency and the maintenance and reinforcement of the dikes.
