The invention provides a static stiffness calibration device for a mooring cable in air. The device comprises a vertical screw rod, a vertical frame, a wall fixing plate, a vertical sliding table, a horizontal frame, a horizontal sliding table, a horizontal ball screw rod, a servo motor, a driver, a control cabinet and the like. The wall fixing plate is connected with a wall body. The fixing plateis fixedly connected with the vertical frame. A vertical sliding block is arranged on the vertical frame. One end of the screw rod is connected with a mounting frame through a first bearing assembly,and the other end of the screw rod extends into a motor mounting seat and is connected with a second bearing assembly. A driving axle is connected with the screw rod through a transmission component.The horizontal frame is connected with the vertical sliding block. One end of the horizontal ball screw rod is connected with the horizontal frame through the first bearing assembly. The other end ofthe horizontal ball screw rod extends into the motor mounting seat and is connected with the second bearing assembly. The driving axle is connected with the screw rod through the transmission component. A horizontal sliding block is arranged on the horizontal frame. The work is reliable.