The instantaneous angle of attack on the blade has a significant effect on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades. This paper investigates the influence of different preset angles of attack on the hydro-dynamic performance of a three-bladed, vertical-axis, tidal-current turbine both experimentally and numerically. Experiments are carried out in a towing tank. This tested turbine’s solidity is 0.1146. The preset angles of attack on the blade are -3°, 0° , 3° , and 5°, in the experiments. Experimental results show that with the increase of the preset angle of attack from -3°, to 5° , the hydrodynamic performance of the turbine is improved significantly with the power coefficients being increased from 15.3% to 34.8%, respectively. Compared to the result of a 0° preset angle of attack, the performance of the turbine with positive preset angles of attack is experimentally demonstrated to be beneficial. This performance improvement is also shown by numerical The instantaneous angle of attack on the blade has a significant effect on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades. This paper investigates the influence of different preset angles of attack on the hydro-dynamic performance of a three- The blazed, vertical-axis, tidal-current turbine both experimentally and numerically. Experiments are carried out in a towing tank. This tested angles of attack on the blade are -3 °, 0 °, 3 °, and 5 °, in the experiments. Experimental results show that with the increase of the preset angle of attack from -3 °, to 5 °, the hydrodynamic performance of the turbine is improved significantly with the power coefficients of increased from 15.3% to 34.8 Compared to the result of a 0 ° preset angle of attack, the performance of the turbine with positive preset angles of attack is experimentally demonstrated to be beneficial. This performance improvement i s also shown by numerical