The invention discloses a testing device and a testing method for performing cross-point testing on the shear dynamic stiffness of an air spring. The testing device comprises a mounting frame, a testing frame and a load application part, wherein a load sensor is arranged on the mounting frame, the testing frame is arranged on the load sensor, the load application part is arranged at the top of the mounting frame, the load application end of the load application part extends into the testing frame, two mounting spaces for mounting a pair of air springs are formed between the load application end of the load application part and two side parts of the testing frame, a displacement sensor is arranged on the load application part, and a protective frame arranged on the periphery of the testing frame in an enclosing manner is also arranged on the mounting frame. The testing method comprises the following steps: 1, mounting; 2, testing; 3, recording; 4, obtaining of a testing result. The testing device and the testing method have the advantages of convenience and safety for use and capability of improving the testing accuracy and stability.