The fixed denture supported by multiple implants can effectively improve the retention and stability of traditional complete dentures, and greatly improve the masticatory ability and life quality of patients, which has been proven to be a reliable treatment method. However, how to accurately obtain the position and posture of multiple implants while the patient feels comfortable is still one of the main clinical difficulties. We design a four-camera system and propose its corresponding method, which accurately measures the position and posture of stereo probes (note that the stereo probes are finely screwed on the implants, i.e., the coordinate systems of the implants are transferred to the stereo probes). In the calibration, a ChArUco calibration board is introduced and the calibration parameters are derived utilizing the proposed three-stage calibration strategy. In the measurement, the stereo probes are screwed on the implants and captured by the four-camera system. Through Canny/Devernay method, the gauge points on the surface of the stereo probe can be solved. Subsequently, the decoding of the gauge points and stereo probes is achieved by the implementation of the proposed matching and decoding strategy. In addition, to achieve higher accuracy, a refinement approach under multiview for the position and posture of stereo probes is established. The result of the experiments verifies that our system and method have higher accuracy and effectiveness (note that the distance error between the two stereo probes is about 19 μm), which is entirely satisfactory for the application of digital implant impressions.