In this study, the characteristics of flow and bed changes with variation of space and length of serial spur dikes were investigated with 2 dimensional numerical simulation. Upstream spur dike was affected by flow and made a role as a single spur dike. As time increased, local scouring was developed around outside of spur dike, and migrated upstream. The aggradation of the bed at the back of spur-dike was made at the initial stage of experiment and numerical modelling. However, the aggradation of the bed was increased in the downstream area. The scour whole around a spur dike upstream was not deep as the Dimensionless spur-dike interval () of the dike increased. The depth of scour hole was nearly constant at the dynamic equilibrium state. The dimensionless scour depth () increased with . The spur dike downstream had the characteristics of single spur dike as the was larger than 10. However, the spur dike downstream was affected by the dike upstream as the was less than 4, and the bed of the upstream in the spur dike was aggradated and the effects of the serial spur dikes on the bed decreased.