Reasonable development and utilization of wind power is an important way to alleviate the current crisis of fossil energy. In order to improve the utilization rate of wind power

and to optimize the design of vertical axis wind turbines

a structure improvement scheme of vertical axis wind turbine about aerodynamic performance is put forward

namely placing an deflector on upstream area of two counter-rotating straight-bladed vertical-axis wind turbines（VAWTs）. Through studying the parameters of deflector two vertical axis wind turbine energy

the width of deflector has the greatest impact on obtain wind energy. The influence of distance between the two turbine shaft and the deflector on wind power obtained is positive at first

but then negative.With the increase of distance between the two vertical axis wind turbine shaft and rotor diameter ratio

the maximum wind energy obtain by the fan gradually decreases. When the parameters of the deflector is appropriate

the maximum wind energy utilization ratio is 0.45

which is increased by 36%

compared with the cases without deflector.