The aim of this study is to investigate the performance of an innovative vertical axis turbine which possesses the blade-self-deflection function for ocean current and tidal energy application. The blade deflection is accomplished by interaction of blades and related mechanisms as the turbine rotates. To enhance the turbine performance, it is designed that the blade deflection not only increases the power output for a downstream blade, but also decreases the resistance for an upstream blade. The observation of the prototype in laboratory flume is displayed to validate the feasibility. Furthermore, a commercial code is employed to analyze the turbine performance. The velocity and pressure contours of the calculation domain are simulated to obtain the torque and power output of deflectable-blade turbine. Moreover, the results of performance analysis are validated by the experimental data. The detailed flow field analysis and hydrodynamic characteristic are reported as deflectable-blade turbine is driven by the water stream. The results show that the maximum and minimum total torque for this turbine occur at theta = 45 degrees and theta = 75 degrees, respectively as it rotates one-quarter turn. In performance comparison, the maximal power coefficient of the deflectable-blade turbine is 41.1% higher than that of traditional vertical axis turbine with fixed blades for stream velocity of 1 m/s. Furthermore, the correlations of optimal angular velocity and maximal power output for the deflectable-blade turbine are obtained for current velocity from 0.6 m/s to 2.2 m/s for hydropower applications. (C) 2016 Elsevier Ltd. All rights reserved.