In view of the settlement and collapse occur easily at riprap spur dike,the prototype observation is carried out for the riprap spur dike used in the waterway regulation at Longxu channel of the Xijiang River and Jilongzhou shoal to investigate the main influential factors on the stability of the spur dike body.Based on the comparison and analysis of sediment movement prototype,this study found that,the scouring damage of the spur dike foundation is the main factor that causes dike body’s instability.To enhance the ability of preventing erosion,the spur dike foundation should construct with sandbag or gravel or stone slag.The result may serve as referenced technology for waterway regulation on the riprap spur dike in the sand shoal.