The calibration of camera with wide field-of-view is a challenging problem because a target of large scale is hard to machine,while using target of small scale cannot satisfy the required accuracy. A camera calibration method based on flexible three-dimensional(3D) target is proposed to solve the calibration problem of camera with wide field-of-view. Flexible 3D target is a target consisting of several planar targets,called sub-targets,which are placed flexibly according to the range of the camera′s view-field. The coordinate frame of the flexible 3D target is constructed based on a sub-target. By using the invariance of the relative positions between sub-targets in the flexible 3D target,the local coordinate frame of each sub-target is transformed into the coordinate frame of the flexible 3D target. By minimizing the re-projection error of feature points on all the sub-targets,the maximum likelihood estimate of the camera parameters can be obtained. Synthetic and experiments show that the accuracy of the proposed calibration method is almost the same as the calibration method using a big planar target whose area is similar to that of the flexible 3D target.