Aiming at overcoming the problems that the traditional modal testing methods have limited information and the transducer additional mass effects modal parameters, and existing noncontact modal testing method requires complex image processing, a vibration modal measurement method for thinwalled parts using optical flow point matching and tracking is proposed. It avoids complicated image processing such as feature segmentation and extraction and so on in each frame. Firstly, the model of vibration detection based on the inplane vision is developed. The intrinsic and extrinsic parameters of industrial camera are calibrated through the camera calibration board, and the errors are analyzed. The principle and the method of monocular vision vibration testing based on optical flow method are investigated. The vibrating sequence images of structure which has pasted feature points are captured with a monocular industrial camera. The pyramid LucasKanada algorithm is used for optical flow point matching and tracking, and to get the vibration information of each subpixel feature point. And then the modal parameters are obtained by modal parameter identification. Based on the proposed method, a thinwalled vibration modal testing system is built and the vibration modal testing experiments with the thinwalled beam is investigated, the testing results are compared and analyzed between that of a shaker testing and FEM simulation. The results show that the natural frequency errors are less than 5% and the corresponding vibration modes are the same, which verifies the correctness of the proposed method, so the proposed method provides a new way for the vibration modal testing of thinwalled parts.