In the present work, passive control of vortex shedding behind a circular cylinder by splitter plates of various lengths attached on the cylinder base is experimentally investigated in shallow water flow. Detailed measurements of instantaneous and time-averaged flow data of wake flow region at a Reynolds number of $Re=6300$ were obtained by particle image velocimetry technique. The length of the splitter plate was varied from $L∕D=0.2$ to $L∕D=2.4$ in order to see the effect of the splitter plate length on the flow characteristics. Instantaneous and time-averaged flow data clearly indicate that the length of the splitter plate has a substantial effect on the flow characteristics. The flow characteristics in the wake region of the circular cylinder sharply change up to the splitter plate length of $L∕D=1.0$. Above this plate length, small changes occur in the flow characteristics.