The water damage of riprap spur dike in waterway regulation buildings is very serious and its reliability and service life are difficult to predict accurately.In order to solve this problem,the combination of flow process and maximum impact depth is studied experimentally and numerically through flume physical model test with unsteady flow process as control condition.The failure criterion of riprap groves is defined and the probabilistic model calculation method of the combination of flow process and maximum impact depth is obtained by using basic statistical theory.This method can be used for reference to improve the reliability of waterway regulation buildings,and can also be used as a reference for waterway management departments.