Abstract: By means of experimental modal analysis for a jointcantilever plate with one end fixed, the first natural frequency andmodal shape are determined. The joint plate istreated as a joint cantilever beam.The transfer matrix method is implemented with thecomputer algebra language. The equation for the angle stiffness is obtained. With the first natural frequency ofthe joint plate as an input, the angle stiffness can be determined. Thevalidity of this method is shown by experiment.