The invention provides a grasping test device based on multi-direction instantaneous mutation disturbance torque effect and a method thereof. The grasping test device comprises a hollow casing, wherein the hollow casing contains a fluid; the inner wall of the hollow casing is provided with a torque sensor for detecting a side force of the thumb, and the opposite side of the inner wall of the hollow casing is provided with a torque sensor used for detecting four-finger side forces; the hollow casing is disposed on a base, and is connected to an electromagnet device at the bottom of the base; the electromagnet device is configured to generate the instantaneous mutation disturbance torque acting in a specified direction on the bottom of the base; the torque sensor detects a data signal of a test subject under the action of the instantaneous mutation disturbance torque, and the data signal is used to perform processing to evaluate the hand grasping function. Under the framework of the uncontrolled manifold (UCM) hypothesis, the index of multi-finger dynamic signal synergy is calculated to evaluate the stable synergy of multi-finger finger force, and the quantitative evaluation of the precise grasping function of the hand is carried out.