The invention discloses a device for grasping an electromagnetic transducer to assist nondestructive testing and a trajectory planning method of the device. The device comprises two mechanical arms and a binocular camera, two mechanical arms are correspondingly arranged on a mechanical arm supporting base around a testing platform, the binocular camera is arranged on a supporting frame around thetesting platform, each mechanical arm comprises a first rotating shaft, a supporting column, a first mechanical arm, a fixing device, a steering gear, a second mechanical arm, a second steering gear,a second rotating shaft, a mechanical claw and a speed reduction motor, the bottom of the supporting column is connected with the supporting base through the first rotating shaft, the first mechanicalarm is fixed at the top of the supporting column, one end of the first steering gear is connected with the first mechanical arm through the fixing device, the other end of the first steering gear isconnected with one end of the second mechanical arm, the other end of the second mechanical arm is connected with one end of the second steering gear, and the other end of the second steering gear isconnected with the mechanical claw through the second rotating shaft; and the speed reduction motor is arranged on the mechanical claw and connected with a gear of the mechanical claw.