The invention provides a dynamic calibration system, and a combined optimization method and a combined optimization device in the dynamic calibration system. The dynamic calibration system comprises a marker geometry feature extraction module, a camera parameter estimation module and a calibrate result evaluation module; the marker geometry feature extraction module detects a marker in the image shot by the camera, extracts geometry features of the marker, and traces and matches the extracted geometry features on images of follow-up frames which are provided by the camera; the camera parameter estimation module is used for obtaining the error of repeated projection according to the extracted geometry features of the marker and current poses of various cameras and obtaining a calibration result when the repeated projection error satisfies a set error threshold; all cameras are positioned in initial position states during the first operation; and the calibration result evaluation module is used for evaluating the accuracy of the calibration result and determining whether to receive parameters of the calibration result. The calibration parameter of the invention has relatively high accuracy, and the dynamic calibration system, the combined optimization method and the combined optimization device in the dynamic calibration system are applicable to the dynamic streamline calibration, high in execution efficiency, wide in application range and simple in system.