Slow water bodies， mainly represented by landscape lakes and ecological wetlands， are becoming more and more important in urban construction. How to increase water exchange areas and slow down the deterioration of water quality is an important problem we are faced with. Based on particle image velocimetry （PIV） technique， the effects of spacing ratio， diversion flow rate and shape of double bluff body （islands） on two-dimensional flow field distribution， water displacement rate and average velocity of the flow field in slow water are studied. The experimental results show that the diversion flow rate is the main controlling factor for the intensity of the flow field in the slow water， and the hydrodynamic exchange efficiency and the average velocity of the water flow are proportional to the diversion flow. The bluff body can obviously improve the range of flow movement and increase the fluidity of water. It is found that the fluidity of the flume water is the strongest and the displacement rate is the highest when the prism and cylinder are disturbed together. The maximum displacement rate reaches 72.89% when Q=6.8 L/min and G/D=6. The experimental results will provide some reference for optimizing the layout of islands in the landscape lake.