The riprap spur dikes are widely used in waterway regulation projects，which can clearing sands with the converging flow，and protect the beach from erosion. However，the damage of riprap spur dike frequently occurs. For this phenomenon，movable-bed physical model tests are conducted on the damage of dikes in plain-river，and the common damage forms of spur dike are analyzed. It is believed that the collapse and loss of the block stones at the dam head are considered as the main factors causing the overall damage of spur dikes. That is，the stability of riprap spur dikes can be studied based on the damage of dam heads. Then，the meaning and solution method of flood damage evaluation indicator，and damage grade at the dam head are put forward. The indicator values of different damage degrees are given in combination with damage grade. As a recommendation，the selection of the maintenance time of the dike is provided. This method provides a new solution for the maintenance of riprap spur，and is conducive to the sustainable development of the regulation effect of riprap spur dikes.