Abstract: To study the effect of flow deflector angle on the hydrodynamic performance of otter board, a flume model experiment was conducted to measure the lift coefficient (CL), drag coefficient (CD) and lift to drag ratio (K) of two flow deflector vertical cambered otter boards, each with three kinds of flow deflector angle. The experimental results show that: 1) For the single flow deflector vertical cambered otter board, when the angle of attack was between 20~35, the CL and CD values showed a downtrend with increase of flow deflector angle. In this case the otter board D1 (flow deflector angle was 35) showed better hydrodynamic performance. 2) For the double flow deflector vertical cambered otter board, when the angle of attack was between 25~35, the otter board S3 (the front flow deflector angle was 20 and the middle flow deflector angle was 25) showed better hydrodynamic performance. It is suggested that the best working scope of angle of attack of otter board D1 was between 15~30, in that case, CL1.2 and K2.0; the best working scope of angle of attack of otter board S3 was between 20~30, in that case, CL0.8 and K3.0. The critical angle of attack of lift coefficient increased with increase of flow deflector angle. Properly regulating flow deflector angle couldoptimizethehydrodynamic performance of otter board.